The tens of thousands of people cheering here in Grant Park, at what is shaping up to be one of the largest victory celebrations in U.S. political history, are not just heralding another barrier broken in America. They are honoring a promise fulfilled — the advancement of a rare political leader who addresses the public honestly, engages his opponents respectfully and communes with his supporters openly. He built an agenda through a participatory politics that empowers organizers and upends civic culture by expanding the electorate.

In political terms, that means that Obama did not win “red states” Tuesday by treating them like red states.  He did not energize his base by neglecting it.  He did not convert wing voters by pandering to their occupational and cultural identities.  After all the soundbites piled up, in fact, it was still Obama who had an actual policy conversation with Joe the Plumber, while Sen. John McCain invoked the everyman as a human prop.

Across the country,  people,  with their votes and their activism, are embracing the “change” agenda. Some scuffling over credit, priorities and ideology is inevitable, but the basics are clear: end the Iraq war; renew the economy; conquer corruption; prioritize alternative energy; pursue universal health care; and renew our civic life with a politics of good faith.  It is ambitious, difficult and long overdue.

Security appears more onerous than usual.  One person told me they knew people who got in line at 4 p.m. and were still waiting four hours later to get in. Some gates did not open to the public until 6 p.m.  But those who made it inside are boisterous, from what I could tell from a recent walk around the grounds. People cheered wildly at the news that Pennsylvania’s 21 electoral votes were in the Obama column, according to CNN and MSNBC.

For what it’s worth — very little — the press here is convinced Obama will win by a lot tonight.

Traveling aides told me they’re just happy that their two-year national tour is over.  Several reporters sheepishly said that no matter what happens, they just hope this race is called early tonight.  One person is circulating an “off the record” election night pool for press people who want to play the odds, but few seem psyched to play. No one is listening to the CNN pundits droning on the big screens here. In fact, I’m most struck by the general blase attitude in the cavernous white tent the Obama campaign built for its high-tech, high-priced “press file.” Writers and bloggers without $900 to spare are stuck on a set of bleachers outside, sans power or heat.

Organizers work in Missouri today. The Obama campaign has been uploading pictures of its GOTV operation in real time. (Credit: Obama Flickr.)

Now, maybe I’d like to augment this post with the contrast of excited supporters filling the fields here, but first, most people have not arrived, and second, we can’t really get close to most of the audience areas.

Earlier today, however, I visited a local field office packed with volunteers making calls to Ohio and Pennsylvania — and there was zero exhaustion there. People were pumped, reading off their calling scripts, posing for pictures in front of homemade Obama signs, and trading excited plans for election night.  I can’t see them here at Grant Park, but I know they’ll be here tonight.

There’s a small strip of coveted real estate between the stage and the largest bank of TV cameras I’ve seen on the campaign trail this year. The rest of the crowd will fill out a huge aisle of the park, facing the stage at something like an 80-degree angle. Most will watch tonight’s speech on JumboTrons dotted throughout the park. (There are almost no attendees here yet.)

In the press filing center, CNN is playing on two big screens, and about 100 reporters are milling about the half-empty tent. People are buzzing over some early, unreliable exit polls that suggest Obama leading in virtually every key state. As Laura just posted, exit polls are hardly a basis to buzz in any direction.

Meanwhile, Obama has been (finally) relaxing — he played basketball with friends and returned to a nearby hotel at about 5:10pm.