Mayor Bloomberg’s promotion of a centrist government that would transcend party politics is driving a new approach to American politics, and efforts to downplay the viability of his possible presidential campaign are premature, a political strategist and pollster who has worked for Mr. Bloomberg and President Clinton is saying.

Douglas Schoen said the argument that Senator Obama’s victory in the Iowa caucuses and strong showing in the New Hampshire primary closes the door on a presidential campaign by an independent Mr. Bloomberg is shortsighted.

The idea that Mr. Bloomberg’s campaign may be a nonstarter because of Mr. Obama’s surge is flawed because “a week and a half ago you would have had a completely different” take on the race, he said, a reference to the prevailing wisdom in some political circles that Senator Clinton was the inevitable Democratic nominee prior to the Iowa caucuses.

Mr. Schoen said Mr. Obama’s surge and an anticipated comeback by Senator McCain, a Republican, is due in part to the candidates’ adoption of Mr. Bloomberg’s message of bipartisan cooperation.

Mr. Bloomberg “is really the catalyst of a large movement in American politics,” he said. The mayor is “driving broader trends in American politics today, and I think he is a central actor in the process, if not the central actor.” Mr. Schoen, the author of “Declaring Independence: The Beginning of the End of the Two-Party System,” which is due out from Random House next month, said he thinks there is “a very real chance” Mr. Bloomberg will run for president. He argues in his book that a third-party candidate could take the White House this year. Mr. Schoen has said he has no expectation of working for Mr. Bloomberg, should he launch a campaign.

He would not comment on what it would mean for a possible Bloomberg presidential campaign if Mr. Obama were to win the Democratic nomination, an event which some observers say would make it difficult for Mr. Bloomberg to enter the race because Mr. Obama already has adopted some of the unifying rhetoric that would be expected to be the center of a Bloomberg campaign. He said there is a long way to go before the nominees are chosen.

On Sunday and Monday, Mr. Bloomberg brought his call for a unifying government that focuses on solving problems to Norman, Okla., where he met with 16 other current and former elected officials at a bipartisan summit at the University of Oklahoma. Participants called on presidential candidates to explain how they would solve problems through bipartisan consensus and establish a government of national unity.

David Boren, a former senator who is president of the University of Oklahoma, who co-hosted the forum with a former senator of Georgia, Samuel Nunn, said on Monday that he was seeing some encouraging signs of bipartisanship from the presidential candidates. Mr. Bloomberg said he hoped Mr. Boren was right.

Several press reports from the summit argued that momentum behind a potential presidential run by the mayor was subsiding in the face of Mr. Obama’s recent surge. Newsday’s political Web log, Spin Cycle, suggested in a posting that Mr. Bloomberg’s presidential dream may “die in New Hampshire,” writing that if the ascendant candidates, Messrs. Obama and McCain, are popular with independent voters, “how does he make the case that America needs him as the third man in?”

Andrew MacRae, a supporter of Mr. Bloomberg’s who blogs for uniteformike.com, a Web site calling for a Bloomberg presidential run, said he doesn’t agree with the sentiment that Mr. Bloomberg’s possible campaign is running out of steam before it even starts.

“These are the same people who were saying Hillary Clinton was inevitable six months ago,” he said. “Things are so polarized that I think the opportunity for a third party or something genuinely different isn’t diminished by Barack Obama’s presence at all.”