NORMAN, Okla. — He arrived here for what seemed like it could be a big moment. Mayor Michael R. Bloomberg, eyeing a third-party presidential bid, joined Republican and Democratic elders at a forum to denounce the extreme partisanship of Washington and plot how to influence the campaign.
But even as the mayor gathered on Monday with the seasoned Washington hands on the campus of the University of Oklahoma, the surging presidential campaign of Senator Barack Obama seemed to steal energy from the event and set off worry elsewhere among Mr. Bloomberg’s supporters.
Mr. Obama has stressed that he wants to move beyond gridlocked politics and usher in an era of national unity. A key organizer of the effort to draft Mr. Bloomberg for a presidential run acknowledged in an interview on Monday that that Mr. Obama’s rise could be problematic.
“Obama is trying to reach out to independent voters, and that clearly would be the constituency that Mike Bloomberg would go after,” said Andrew MacRae, who heads the Washington chapter of Draft Mike Bloomberg for President 2008. “An Obama victory does not make it impossible, but it certainly makes it more difficult.”
The event was organized by former Senator Sam Nunn, Democrat of Georgia, with former Senator David L. Boren, Democrat of Oklahoma. In the days leading up the event here, just outside Oklahoma City, Mr. Boren suggested that he would encourage Mr. Bloomberg to run if the major party nominees failed to heed the call for bipartisanship.
But several leading participants took pains to say that they had no intention of abandoning their own parties in the election. Some even cast Mr. Obama’s success as evidence that the nation was yearning for the type of leadership they were offering.
“I believe he is demonstrating, in the support he is getting, that the American people share this concern about excessive partisanship,” said Bob Graham, a Democratic former senator from Florida, who said he would support a Democrat for president.
Gary Hart, a Democrat from Colorado who also served in the Senate, said he intended to endorse one of the Democratic presidential candidates in the next 48 hours, though he declined to identify the candidate.
“I am a Democrat, and I will endorse a Democratic president,” he said. “There are no independent candidates. I won’t endorse a Republican.”
The forum attracted students, faculty members and some who said they were intrigued by a third party approach. Still, they were also taking notice of the momentum Mr. Obama has been gaining since his victory in the Iowa caucuses last week.
“I wonder about all this,” said Tobi Padwick, 36, who drove to the event from Texas. Mr. Padwick said he believed the eventual nominees would be Mr. Obama and Senator John McCain, and “that sort of steals a lot of thunder, since they’re the two more moderate candidates.”
Despite public denials that he plans to run, aides close to Mr. Bloomberg have been laying the groundwork for a candidacy, should he declare one.
Mr. Bloomberg kept a low profile at the forum. In response to a question during the panel discussion about the Iowa caucuses, Mr. Bloomberg did not talk about Mr. Obama or the Republican winner, Mike Huckabee, the former governor of Arkansas, but said that perhaps the discussion the group was looking for had already begun.
“I hope that all the candidates say to themselves that the public is tired of the partisanship and the special interests, and if I’m going to get elected, I’ve got to stand up and say what I believe, face the big issues, hold myself accountable, and maybe you are seeing that.”
As he usually has in recent weeks, Mr. Bloomberg played down the notion that he would be a candidate himself, saying during the forum that the goal he shared with others at the conference was to be a “catalyst” for a discussion of the nation’s problems.
But even Mr. Bloomberg’s effort to influence the debate in the presidential campaign has hit challenges. The mayor recently paid out of his own pocket for ads in Iowa and New Hampshire newspapers demanding, on behalf of mayors concerned about gun violence, that candidates complete a questionnaire detailing their positions on gun issues.
The candidates were given until Jan. 2 to respond, but none of the campaigns complied, and Mr. Bloomberg and his colleagues have now pushed back the deadline.
People close to the mayor say that he will probably decide in March whether he will run, assuming that Democrats and Republicans have settled on their presumptive nominees. His aides have been researching the cumbersome process for starting an independent campaign, and a crucial date is March 5, when third-party candidates can begin circulating petitions to get a spot on the ballot in Texas.
Mr. Bloomberg would have to decide, among other things, whether there was an opening for a self-styled progressive centrist like him. Aides have said that he would be prepared to spend $1 billion.
Other participants at the forum included John Danforth, a Republican former senator from Missouri; Senator Chuck Hagel, Republican from Nebraska; William Cohen, former secretary of defense; and Christie Whitman, former governor of New Jersey and a Republican.
Like other participants, Mrs. Whitman has been seeking to distance herself from any third-party bid by Mr. Bloomberg. In a recent blog post on the Web site of the Republican Leadership Council, a centrist group of which she is co-chairwoman, Mrs. Whitman wrote, “While other attendees may assert their personal interest in a third party, I am a Republican and will remain one.”
Asked Monday whether she would support an independent presidential bid by Mr. Bloomberg or anyone else, Mrs. Whitman echoed those comments, saying, “I’m focused on the Republican Leadership Council.”