As expected, President-elect Barack Obama announced his picks to fill four of the top economic positions in his administration at a press conference today in Chicago.

None of the names came as a surprise, as all of them had leaked out over the course of the past week.

Obama selected: Timothy Geithner, the current head of the New York Fed, as treasury secretary; Larry Summers, a former treasury secretary under President Bill Clinton, as director of Obama’s National Economic Council; Christina Romer, a professor of economics at the University of California at Berkeley, as chair of the White House Council of Economic Advisers; and Melody Barnes, a former chief counsel to Sen. Ted Kennedy and executive vice president for policy at the liberal Center for American Progress, as Director of the Domestic Policy Council.

Flanked by the four nominees, as well as Vice President-elect Joe Biden, Obama said he had already instructed his team to begin working on recommendations for an economic recovery plan, on which he will receive daily briefings. He promised to apprise the American people and the incoming Congress of the recommendations in coming weeks, and encouraged Congress to begin working on an economic recovery package when it convenes in January, so the new administration “can hit the ground running.”

Obama also pledged a round of federal belt-tightening, and said that he plans to “scour the federal budget, line by line, and making meaningful cuts and sacrifices.” He said more details would be forthcoming tomorrow.

Taking several questions from assembled reporters, Obama expressed support for a large economic stimulus plan currently being discussed by many in Congress, but declined to discuss specific numbers. He said this plan should make job creation a top priority, and should invest heavily in infrastructure, health care and education.

I want to see [the economic stimulus package] enacted right away. It is going to be of a size and scope that is necessary to get this economy back on track [...]

The most important thing to recognize is that we have consensus, which is pretty rare, between conservative economists and liberal economists, that we need a big stimulus package that will jolt the economy into shape, that is focused on the 2.5 million jobs that I intend to create. We have to put people back to work.

Appearing on ABC’s “This Week” yesterday, Sen. Chuck Schumer (D-N.Y.) suggested such a package could total as much as $500 -$700 billion.

Obama also reaffirmed his pledge to enact a middle class tax cut, which he said would be “part and parcel” of the economic stimulus package. Obama would not say whether he planned to push for legislation repealing President George W. Bush’s tax cuts for wealthier Americans, or if he would allow them to expire.

However, with the news that the Fed is prepared to make up to $7.4 trillion worth of loans to stabilize roiling financial markets, Obama’s message today seemed designed to reassure middle class Americans that while much of the government’s efforts to prevent economic meltdown have targeted Wall Street, they, too, would receive some relief from Washington.