Mayor Bloomberg’s decision to give a rousing endorsement to Senator Lieberman’s vow to run for election as an independent is stirring speculation on the possibility of the mayor’s own independent campaign for the presidency in 2008.

Mr. Bloomberg, who is now publicly in the midst of weighing his own bid for the highest office in the land, threw his support behind Mr. Lieberman’s third-party candidacy yesterday, saying the country needs “nonpartisan elected officials who think doing the right thing for the public is more important than supporting some party.”

While top Democrats criticized Mr. Lieberman for ditching his party in exchange for a second chance in the election rather than bowing out after being defeated by left-leaning upstart Ned Lamont, Mr. Bloomberg said he would gladly campaign for Mr. Lieberman if asked. Mr. Bloomberg’s support for Mr. Lieberman’s campaign could potentially help his chances if the mayor decides to run for president as a third-party candidate in 2008.

Political analysts said that if Mr. Bloomberg’s independent, nonpartisan style is going to fly, starting the movement now and including others would only work to his advantage.

“It is totally within the realm of possibility that Bloomberg could wind up being a third-party presidential candidate,” a political consultant who worked on John Anderson’s independent bid for the presidency in 1980, Joseph Mercurio, said. “I think it would actually be a smart play for him. He’d have the luxury of getting in at the last minute, which means no one’s sniping at him for two years.That’s not such a bad deal. You don’t have to do primaries, you just have to create an independent candidacy. That’s right up his alley.”

A political science professor at the University of Virginia, Larry Sabato, said that if the mayor decides to run for president, Mr. Lieberman’s run as an independent would bolster his credibility.

“Bloomberg would undoubtedly cite the Lieberman case as a recent example of how an independent can win, assuming that Lieberman actually wins, which is a big assumption right now,” Mr. Sabato said. “If Bloomberg is looking for some justification and precedent, Lieberman could be the answer to his prayers.”

Mr. Bloomberg’s distaste for the two-party system has deep roots. In 2001, the lifetime Democrat ran for mayor as a Republican to bypass a tough primary. In 2003, he invested $7.5 million of his own fortune to push for nonpartisan election. Although the measure was voted down, he never backed away from his conviction that a less partisan approach to politics would open a road to reform.

Since then, the mayor has made his distaste with partisan politics clear, tackling issues, such as gun control, and distancing himself from other Republicans.

“I am not a partisan person, as you know,” he told reporters yesterday at a construction site on Manhattan’s West Side. “I think that political parties, the partisan process, has just hamstrung Washington. It’s paralyzed government at all different levels, not just at the federal level but throughout this country.

“We need people who stand up and call it the way they see it, and that’s what Lieberman does,” Mr. Bloomberg said. He said that while he has not yet been asked, he would be happy to campaign for Mr. Lieberman in the coming months.

The mayor’s chief spokesman, Stuart Loeser, denied that Mr. Bloomberg had any plan to run for president in 2008.

“There’s a distinction between running on a third ballot line and creating a third party,” Mr. Loeser said. “What the mayor was talking about today was Joe Lieberman and elected officials who speak their mind and do what they think is right.” But political analysts said the mayor’s endorsement of Mr. Lieberman’s independent run could prove useful.

“If he is thinking a couple of steps ahead it fits perfectly strategically,” a professor of public policy at Baruch College, Douglas Muzzio, said. “Mike Bloomberg’s thinking ahead could take three nonexclusive forms. One is he is laying out a national agenda. Two, he is laying out a national agenda with the eye toward creating a third party or this other movement. And three, he is thinking of laying the groundwork for this organization with him as its presidential candidate in 2008.”