Independent voters could be pivotal in November. While membership in traditional parties has weakened in recent decades, independent voters increased — the number of people registering as "unaffiliated" or "other" since 1987 jumped from 16 percent to 24 percent. For example, in Florida, an important battleground state, the number of "other" voters has more than quadrupled, surpassing 20 percent of the electorate. In another key state, California, since 1988 the percentage of voters "declin[ing] to state" a party preference rose nearly 8 percentage points — to almost 18 percent.

The looming battle between McCain and Obama for independent voters is evident in polling. On Wednesday, Gallup released a poll that showed McCain and Obama share nearly equal support among independents — 44 percent for Obama and 42 percent for McCain. So this election would ultimately be about who attracts the most independent voters.

Polling also reveals that McCain and Obama both satisfy what independents are looking for in a candidate – personal values, military judgment, willingness to work with the opposing party and managerial competence. So while the national environment may favor Democrats, this suggests that McCain still has a fighting chance to win over these important voters.

"The vital political center is back this year after it was on sabbatical in 2004,” said John Zogby, the eponymous pollster. "The middle, mostly represented by independents, is up for grabs. And it will be the swing vote in the election."

But while the "middle" is likely to be contested, independent voters are often improperly defined. A closer look at this group reveals it is not nearly as monolithic as usually portrayed. Blocks of independent voters vary across the country and, demographically, the differences can be substantial. For example, independent voters in Colorado, often new to the state, are largely young and well-educated. They have different values than independents in, say, Pennsylvania, who are likely to be older, less educated and more rooted in their community. Consequently, independents in certain areas will be more receptive to Obama’s change message while those in other regions will be more likely to support McCain’s established maverick image — a result that could split the independent vote in November.

In addition, the influence of independent voters can be minimal. Experts say independent voters are often the least politically active and, consequently, tend not to vote. Most of the uninformed independent voters tend not to make a rational, personal decision on which candidate to vote for, but are instead swept up into national trends. A growing yet still small class of informed independent voters, it appears, behaves the same way.

One problem that often arises in discussing independents is how large a percentage they are of the electorate. The American National Election Studies (ANES), a group that surveys voters across the country every election year, measures voter partisanship by asking if voters to rank their partisanship on a seven-point scale from extremely liberal to extremely conservative. On this scale, 26 percent said they were "moderates" in 2004, a four point jump from 2002.

But this doesn’t accurately identify independent voters, said Candice Nelson, a political scientist at American University and co-author of "The Myth of the Independent Voter." Two questions must be used to determined partisanship, Nelson said. First, respondents should be asked if they consider themselves a Democrat, Republican or independent. Nelson has found that roughly 30 percent will say they are independents. But then a second question asks if the respondent considers him or herself an independent, does he or she lean toward one party. This greatly reduces the number of independents, for Nelson has found that "leaners toward a political party act in practice just like party members."

True or "hard" independents typically make up just 10 percent of the electorate, according to ANES. They tend to be the "least interested in politics," Nelson said, "and the least likely to vote."

"If you are not quite sure what should be done or where you belong," said Morris Fiorina, the Stanford political scientist and author of "Culture War: The Myth of a Polarized America," "you are going to be attracted to a candidate that gives off that same sort of impression rather than someone who speaks like he knows everything."

These voters tend to be less educated, Nelson pointed out, which is the best predictor of whether someone will vote. "It’s going to be hard," she said, "for both McCain and Obama to motivate this group" to turn out at the polls.

Other experts doubt the significance of the independent vote. Larry Sabato, the director of the Center for Politics at the University of Virginia, estimates that 15 percent of the electorate are "hard" independents this year. He says the group is made up of both the least interested voters and the most informed voters, who tend to vote based on specific issues. Either way, these voters tend to be more influenced by the national environment than individual candidates.

"Both types, assuming they vote, are pushed by the currents disproportionately into one party’s camp each year," Sabato said. In 2002 and 2004, Sabato said, the GOP benefited because the national electorate was still receptive to President George W. Bush and his war on terror. In 2006, Democrats carried this group when Bush’s approval rating plummeted and disapproval of the war in Iraq skyrocketed. Those same issues, plus the slowdown in the economy, Sabato said, will likely push independent voters to the Democrats again this year.

Of those independents resistant to national trends, certain criteria of what they are looking for have emerged, said Zogby. In poll after poll, independents want a candidate that, in ranked order, is a competent manager, can work with both parties, can command the military and has strong personal values. Obama, Zogby said, has convinced these voters that he can work with Republicans, that he has strong personal values and, at least on the war in Iraq, has sound military judgment. McCain’s story as a prisoner of war in Vietnam is cited to prove he has a strong personal values and understands the military. His maverick brand also resonates as bipartisan. Both candidates, Zogby said, will fight to prove they are competent managers.

This also suggests that even in a political environment where Democratic voter turnout is soaring and the GOP is losing congressional seats in districts it has held for years, if McCain can prove he is a competent manager, he could win over independents crucial in a close election.

Appealing to this group isn’t as simple as it seems, though. These independent voters, and their values, vary across the country, said William Frey, a political demographer at the Brookings Institute. The difference is often age, rootedness in community and economic situation, Frey said.

Swing states like Pennsylvania, West Virginia, Ohio and Michigan have older populations that have lived in their communities all their lives. These states’ populations are in decline, and their metropolitan centers are shrinking. Independents in this region have been hit hardest by the current economic downturn, but they hunker down and rely on their communities to persevere instead of seeking radical change.

These independents are often regarded as Reagan Democrats, voters that left the Democratic Party for Ronald Reagan in 1980 and have yet to return. Pennsylvania in particular, Frey said, has a large percentage of "more traditional Reagan Democrats that have stuck their ground." Unsurprisingly, these independents are more likely to support McCain because of his age and military service and are skeptical of Obama’s message of change.

Conversely, states where the population has grown rapidly in recent years, swing states like Colorado, Nevada and New Mexico, have a growing economy. These states also have a growing base of independents. These are "younger people, people on the move who relocate to these states because they have aspirations for their own future and for the communities they are moving to," Frey said, "They are less tied down to old ways of thinking then people who have stayed where they are for years." These voters are open to change he explained. "In these states," Frey said, "Obama may be more appealing because he is fresh and has new ideas."

Independent voters, Nelson explained, are more complex than often portrayed. "The key is how independents are defined," she said, "it is not a monolithic group – some lean to one party and others lean to the other. They are really different groups. If you look at pure independents over the years, they tend to vote for the candidate that wins."

"But when it’s a close election," Nelson added, "they tend to split."

Today Obama struck back.

"After almost eight years, I did not think I could be surprised by anything George Bush says, but I was wrong," Obama, avec flag pin, said.

"The president did something that presidents don’t do..that is launch a political attack targeted toward the domestic audience…in front of a foreign delegation."

Obama also went on offense, attacking Bush and Sen. John McCain (R-Ariz.) for their foreign policy positions, which he called one and the same. "I want to be perfectly clear," he said, "if George Bush and John McCain want to have a debate about protecting the United States of America, that is a debate I am happy to have any time, any place. And it is a debate that I will win."

Obama called his approach to foreign policy "tough diplomacy" and also said he never claimed he would negotiate with terrorist groups like Hamas.

A couple thoughts on this entire exchange: First, it is interesting how forcefully Bush, with his sub-30 point approval rating, can influence the presidential race. And there is no question he knew what he was doing. Second, the Obama camp clearly views the perception of Obama being weak in his support of Israel as a soft-spot. Consequently, Obama has been on a all out media tour to promote his support of Israel. (Obama has recently given interviews on Israel to the Atlantic’s Jeffrey Goldberg, The New Republic’s Martin Peretz, and the New York Times’ David Brooks.)

Third, that being said, Bush’s remarks may actually be a gift for Obama since they shift the campaign narrative from his big loss in West Virginia and have unified the party behind him (even Sen. Hillary Clinton (D-N.Y.) criticized Bush), as MSNBC’s First Read noted.

Fourth, even so, does Obama want his campaign to be defined by his position on Israel? Bush certainly framed the campaign debate yesterday, it will be interesting to see how long this dialogue plays out.

I was just going through the list of unpledged superdelegates, picking out which are the big names left. Besides the obvious choices (Pelosi, Carter, Gore), Waxman and Berman were near the top of the list. I’m expecting Obama to continue rolling out supers,  but saving a few for after Kentucky next week, where Clinton will likely win big again.

‘Israel is a critical American ally and a beacon of democracy in the Middle East, not a ‘constant sore’ as Barack Obama claims,’ Boehner said. ‘Obama’s latest remark, and his commitment to ‘opening a dialogue’ with sponsors of terrorism, echoes past statements by Jimmy Carter who once called Israel an ‘apartheid state.’’

As ABC points out, this doesn’t quite mesh with the interview since Obama directly dismisses Carter’s "apartheid" statement.

Boehner’s remarks angered Golberg, who this morning responded on his blog blasting the minority leader. Golberg says that Boehner must have simply not read the entire interview, since "Obama expressed – in twelve different ways – his support for Israel to me." He adds these choice words:

Boehner’s statement [is] mendacious, duplicitous, gross, and comically refutable. So Mr. Boehner, do the right thing, and correct the record. I’ll be happy to post the correction right here.

Strong words, to be sure. Don’t count on Boehner responding to this, but it will be interesting to see how this continues to play out. Stay tuned.

I think that the idea of a secure Jewish state is a fundamentally just idea, and a necessary idea, given not only world history but the active existence of anti-Semitism, the potential vulnerability that the Jewish people could still experience.

…

That does not mean that I would agree with every action of the state of Israel, because it’s a government and it has politicians, and as a politician myself I am deeply mindful that we are imperfect creatures and don’t always act with justice uppermost on our minds. But the fundamental premise of Israel and the need to preserve a Jewish state that is secure is, I think, a just idea and one that should be supported here in the United States and around the world.

The interview quickly spread. The New York Times ran an article about it in its dead tree edition this morning. While polling and anecdotal evidence suggests that Obama need not worry about Jewish voters, his continued effort to assure Jewish voters of his dedication to Israel shows that it is clearly something his campaign is concerned about going into the fall election. That being said, I don’t know how much more clearly Obama can express his beliefs than he did in this interview and conservative Jews still found room to attack him for this answer:

Goldberg: Do you think that Israel is a drag on America’s reputation overseas?

Obama: No, no, no. But what I think is that this constant wound, that this constant sore, does infect all of our foreign policy. The lack of a resolution to this problem provides an excuse for anti-American militant jihadists to engage in inexcusable actions, and so we have a national-security interest in solving this, and I also believe that Israel has a security interest in solving this because I believe that the status quo is unsustainable.

From the Republican Jewish Coalition:

Once again, Senator Obama demonstrates his questionable grasp of America’s foreign policy. Senator Obama manages to excuse the inexcusable actions of anti-American militant jihadists by putting the blame for their actions on America’s foreign policy. America stands with Israel because it is one of our strongest allies and the only democracy in the Middle East. Senator Obama naively believes that solving the Israeli-Palestinian conflict will solve the global scourge of radical Islamic extremism. Yet Senator Obama never says how he will reign in Hamas’ daily onslaught on Israel or Iran’s scurrilous condemnations of Israel. Is it any wonder Hamas has endorsed him for president?

Maybe this problem really isn’t going anywhere.

The poll, which was conducted as part of Gallup’s tracking poll over April, found that Jewish respondents preferred Obama to Sen. John McCain 61 percent to 32 percent. During April as the Wright controversy exploded, "Rather than declining between March and April," Gallup writes, "support for Obama versus McCain among Jewish voters has increased slightly, from a 23-point margin in favor of Obama (58% to 35%) to a 29-point margin (61% to 32%)."

Even with this numbers, which are quite convincing, why do I have a feeling we still haven’t heard the last of this…

How would that look if at the end of the Democratic race the winning candidate with clearly the most delegates and popular votes went down to defeat against a candidate who isn’t in the contest anymore? Ouch! That would tend to overshadow his expected wins in Oregon and Montana.

…

‘If [Obama] lost to a candidate who’s withdrawn, that would hurt him a lot,’ says Devine. ‘And there’s a good chance that could happen.’

The Times wisely points out that 27 percent of Republicans in the Pennsylvania primary voted for someone other than McCain, a fact that deserves more coverage. Under this theory, Clinton would actually be doing Obama a favor by staying in the race through June 3, when the primaries end, as long as she focusing on attacking McCain and not Obama. Based on her campaign stops over the weekend, it appears Clinton is doing exactly that.

While there have been reports questioning why there hasn’t been a flood of superdelegates to Obama since Tuesday, there certainly seems to be a steady stream. How many would it take for Clinton to consider leaving the race?

(Note: ABC has reported that Obama has now taken the lead among superdelegates, reflecting the difficulty in compiling these lists. I have always used MSNBC’s tally, because I think it is updated most frequently and Chuck Todd is usually on top of these numbers. But, to be sure, here is ABC’s count.)

Hillary has shown she can win the all-important battleground states like Ohio, Pennsylvania and Florida even while being outspent. This speaks to her ability to connect with voters we must deliver in the fall, including blue collar Democrats who can sway this election as they have in the past.

…

Hillary has won rural and suburban districts which we as Democrats must carry to maintain our edge in Congress. Of the fifteen districts rated "toss up" by the Cook Political Report, Hillary has now won ten. Of the 20 districts we picked up in 2006 that had gone for President Bush just two years before, Hillary has now won 16. She is strong in the places we must win to hold and expand our majority.

…

We Democrats are justifiably proud of both of our candidates, and if Sen. Obama is our party’s nominee, we will enthusiastically support him. But our responsibility is not to choose simply to support the eventual nominee; it is to help select the nominee who is best for our party and best for our country. Our choice is clear: Hillary Clinton is that candidate. We believe she should be your choice as well.

While the argument here is nothing new, it’s interesting to see these superdelegates so publicly sticking by Clinton now. Maybe these superdelegates don’t see any harm in Clinton staying in the race as long as she keeps it positive through the last contest on June 3. If Clinton doesn’t bow out shortly after that, the superdelegates will have to step in to end the contest. If they don’t, as I mentioned in my story yesterday, a convention fight would be disastrous for their party in November.

"I think the race is reaching the point now where there are negative dividends from it, in terms of strife within the party," Sen. Dianne Feinstein (D-Calif.), a Clinton supporter, told The Hill Wednesday. "I think we need to prevent that as much as we can."

These concerns stem from some surprising exit poll results. In Indiana on Wednesday, CNN reported that 32 percent of Clinton supporters in Indiana would vote for McCain in the general election if Obama becomes the nominee. That number rose to 35 percent in North Carolina.

For Democrats, these statistics raise the specter of a divided party going into the general election. Many Democrats remember the battles of 1972 and 1968, when the fight continued into the convention and produced nominees – Vice President Hubert H. Humphrey in ‘68 and Sen. George S. McGovern in ‘72 — who lost badly to the GOP nominees.

"If it goes to the convention, that is a problem," said Michael Kazin, a history professor at Georgetown University who studies electoral history and has written a biography off three-time presidential candidate William Jennings Bryan. "When there is a battle at the convention," he said, "the party that has it always loses."

This, combined with Clinton’s close to mathematically impossible route to the nomination and her continuing need to loan money to her campaign, provide fodder for those Democrats who want the New York senator to exit the race. McGovern, in fact, switched his endorsement from Clinton to Obama on Wednesday and urged Clinton to end her campaign.

"The prolonged primary race is clearly going to hurt whoever emerges," said Trent Duffy, a former deputy press secretary for President George W. Bush and current partner at HDMK, a Republican media consulting group. "The longer this goes, the more Democratic voters won’t vote for the nominee if it isn’t their candidate. It’s poisonous for them."

But it remains to be seen whether the prolonged Democratic campaign will actually hurt the party’s candidate in the general election. Little evidence beyond those few exit polls exists to support the claim that the Democratic race is damaging the party’s chances in November yet. Polling suggests the environment this year favors the Democratic candidate and many experts say calls for Clinton to exit now are premature.

Once the nomination is settled, they say, the differences between either Obama or Clinton and McCain, who has been out of the media’s eye recently, will unify the party. Obama, who is now better positioned to take the nomination, will gain the support of Clinton’s base of white, working-class voters. While the focus on the Democratic race might benefit McCain, because Obama and Clinton keep beating up on each other, it also stymies his campaign because he can’t develop a strategy based on his opponent. All this suggests that Clinton doesn’t need to drop out of the race — at least not yet.

"The focus eventually will turn to the nominee," said Mark Rozell, a political scientist at George Mason University. "All the advantages this year look to be with the Democratic Party. I don’t believe any of the polling data that suggest that many Clinton or Obama supporters will abandon their party nominee if it is not their own candidate. Once the choice becomes Democrat or Republican, they come back. It just might take a while for them to warm up to it."

The Clinton camp has, unsurprisingly, espoused this view. On Wednesday, Howard Wolfson, Clinton’s spokesman, was adamant that the prolonged race has increased turnout and excited voters, which is true. Clinton, he said, has no intention of stopping. When asked on a conference call Wednesday morning if there has been any talk of ending the campaign, Howard Wolfson, Clinton’s spokesman, quickly replied, "No. No discussions."

Later, Wolfson was pressed if Clinton ever considers if her prolonged candidacy is damaging the party. "I just reject that analogy out of hand," Wolfson replied. "We believe that this process has been good for the party."

Many experts agree. The political landscape heavily favors the Democratic candidate in November, said Darren Davis, a political scientist at Notre Dame. Pundits and the media are focusing the Democratic fight now, but that will change as soon as the nomination is settled and the Democratic candidate begins to draw contrasts with McCain. "You just can’t perceive Obama or Clinton in a vacuum," Davis said. "It is really difficult to compare how voters are going to perceive Obama and Clinton when McCain has not been the center of attention. Once there are two candidates and the failings of the Bush administration and some of McCain’s weaknesses are brought out, people will begin to assess the lesser of two evils."

"Right now McCain is being given a free pass," Davis added. "If there is one thing that will coalesce Democrats, it will be beating up Republicans."

Some Republicans see the Democrats’ nominating struggle as not entirely benefiting McCain. "It’s a double-edged sword for McCain," said John Feehery, a Republican strategist. "On the one hand it’s good that Hillary will continue to attack Obama and it’s good for him to learn what attacks work. On the other hand, Democrats are dominating the conversations and McCain can’t get in the news."

Moreover, McCain needs the Democratic nomination to be settled so he can develop his campaign strategy. If Clinton is the nominee, Feehery said, McCain will appeal to Reagan Democrats. If Obama gets the nod, McCain will target independents.

Even some Obama supporters have no problem with the long nominating contest. "People forget that we’re in May," said Dan Gerstein, a Democratic strategist who supports Obama. "There are five full months of campaigning left. That’s a lifetime in politics."

If anything, Gerstein said, the prolonged fight has helped Obama. "A lot of good has come out of this. Obama owes Hillary a debt of gratitude for testing him," he said. "Obama has been able to show he doesn’t have a the glass jaw that people feared. He’s a stronger candidate now."

Bruce Schulman, a history professor at Boston University who has studied electoral politics, isn’t so sure. "If Clinton had gotten out a month ago, you wouldn’t have had all of these attacks on elitism, Obama’s inability to attract white middle-class voters and the Wright controversy wouldn’t have been so prominent," said Schulman. "Obama certainly has been weakened and lowered by this campaign."

Gerstein, however, contends that the concern surrounding whether Clinton’s blue-collar base will support Obama is blown out of proportion. "The overwhelming majority of Democrats that voted for Hillary, the Reagan Democrats," he said, "will naturally transfer to Obama" because he is more in line with their values than McCain.

Still, as Kazin noted, if the Democratic race goes too long, a delegate battle at the convention would be damaging for the nominee. But unless her campaign turns very negative towards Obama, hoping to tear him down, Kazin doesn’t see a problem right now.

Matt Klink, a Democratic consultant in Los Angeles, also said a convention fight would be disastrous. Clinton, he said, should look for a "graceful away to exit" in early June. If she doesn’t get out by then, Klink said, "some red flags should go up."