Michael Bloomberg is back in the 2008 presidential picture, and one thing is for sure: There is a statesman-sized hole to fill in the center of American politics.

It would fit a figure who is strong on national security, unlike all the Democratic candidates, yet fiscally responsible and socially moderate to liberal, unlike the Republicans.

It's a Franklin Roosevelt-, Harry Truman-, Dwight Eisenhower-, John F. Kennedy-sized hole that's currently occupied by no one except perhaps Sen. Joe Lieberman, ID-Conn., a man without a party.

The problem with American politics now is that Democrats have driven themselves, once again, to the left end of the political spectrum on foreign policy as was demonstrated once again recently on the floors of Congress and in the Las Vegas presidential debate.

Not one candidate in the debate, nor any Democratic leader in Congress, would acknowledge that important progress has been made in Iraq since Gen. David Petraeus launched his counterinsurgency strategy.

To the contrary, Democrats are playing a dangerous game of "chicken" with the country's armed services, threatening to cut off funding for the military to force President Bush to accept a goal of full withdrawal from Iraq in 2008 despite the chance Petraeus has created for a successful outcome.

It's hard to disagree with what Lieberman has said in the past two weeks that Democrats are "emotionally invested in a narrative of defeat and retreat in Iraq" and that "it is deeply irresponsible for antiwar forces in Congress to hold hostage the funds our men and women in uniform need to continue their successful efforts."

Democrats are following the same pattern in requiring a court order for electronic intercepts of terrorists overseas because they might contact someone in the United States. Democrats act as though Bush presents a greater danger to this country than Osama bin Laden.

Meanwhile, Republicans have driven themselves to the right edge of the economic and social spectrum, as demonstrated by Bush's vetoes of spending and children's health bills, by Republicans' penchant for borrowing to pay for their outsized tax cuts, and by the presidential candidates' hardline positions on abortion and immigration.

Republicans in Congress sustained Bush's vetoes despite their own record of piling up $1.9 trillion in accumulated deficits since he took office and the fact that Democratic spending proposals represent just a $5 billion increase over current levels, designed to pay for student aid, medical research and energy assistance for the poor.

As demonstrated on the House floor recently, Republicans oppose paying for a needed "fix" in the alternative minimum tax with higher taxes elsewhere, preferring to borrow the money from their children and grandchildren.

On the campaign trail, no candidate dares talk about higher taxes to pay America's bills, and there's next to no attention among GOP candidates to the fact that America's middle class feels economically stressed.

And the feeling is legitimate, given a new report showing that upward mobility in the United States lags behind that in other industrialized countries and that only people in the best-educated third of the U.S. population can expect to be better off than their parents.

Except for Sen. John McCain, Ariz., the leading Republican candidates are pandering to a loud anti-immigrant claque in the party and, except for Rudy Giuliani, all are vying to appeal to the right-to-life movement as ardently as Democrats appeal to the abortion-rights movement.

There's a huge gap in the middle that could be filled by a candidate who calls for perseverance in Iraq and tough diplomacy toward Iran, yet also favors adequate funding for education and health care and is moderate on abortion and immigration.

Candidates pay lip service to the public's evident desire for its politicians to stop partisan squabbling and start solving their real problems, but the gap remains wide in view of anyone offering nonideological solutions to those problems.

New York Mayor Michael Bloomberg arguably could fit well into the space, although he has to begin speaking out on national and international issues if he hopes to be successful as an independent candidate.

He is privately telling visitors that the chances of his running are 50-50. Clearly he wants to keep a buzz going about his candidacy, having cooperated with Newsweek in a cover profile two weeks ago. The article exhaustively covered Bloomberg's life, mayoral record and political prospects but was short of details on his views.

He is clearly pro-choice on abortion, pro-gun control, pro-gay rights and favors merit pay for teachers and controls on climate change. His view on Iraq, as expressed in Newsweek, is that "the current situation is intolerable" because "the public doesn't understand why we are there, and part of leadership is explaining, bringing people along."

That could mean explaining why America has to see the task through to success, if it can be attained, but Bloomberg didn't say. It is encouraging that in 2006, he campaigned for Lieberman's re-election.

On the other hand, he sounds like a Democrat on Iran, virtually ruling out military action and promising negotiations. That doesn't necessarily make him a hopeless dove, but he didn't mention the word "sanctions," either. Sen. Hillary Rodham Clinton, D-N.Y., did.

Bloomberg aides say he won't run unless he thinks he can win. A Newsweek poll indicated that, right now, he garners only 11 percent of the vote, to Clinton's 44 percent and Giuliani's 38 percent, and pulls more support from Giuliani than Clinton.

But that's all theoretical because Bloomberg is hardly known outside of New York and its environs. He has to stop teasing and start talking in order for the public to determine whether he is what America desperately needs a centrist choice dedicated to keeping America safe, solving its problems and building consensus.

(Morton Kondracke is executive editor of Roll Call, the newspaper of Capitol Hill.)