The statement by a former U.S. senator of Nebraska that he is considering a run for City Hall demonstrates the weakness of the other Democrats currently striving to replace Mayor Bloomberg, several political consultants said yesterday.

Robert Kerrey, who currently serves as president of New School University at Manhattan, is apparently disturbed by Mr. Bloomberg’s zeal about the West Side football stadium and said he is dissatisfied with the mayor’s lackluster efforts to oppose legislation in Washington that harms New York City, the New York Times reported yesterday.

While a spokesman for Mr. Kerrey confirmed that the former senator is contemplating a mayoral bid, political consultants were skeptical about the feasibility of a Kerrey campaign and questioned the seriousness of Mr. Kerrey’s surprise announcement.

As Mr. Kerrey moved to New York in 2001 when he assumed the New School’s presidency, his newcomer status is not the least of the obstacles to a credible candidacy.

“To be mayor of New York City you probably have to live there for a little more than five years,” a professor of public administration at Columbia University, Steven Cohen, said yesterday.

A longtime New York Democratic consultant, Hank Sheinkopf, seemed to concur. “It’s a long time since we’ve had a mayor from Omaha,” he said.

Mr. Sheinkopf also pointed to Mr. Kerrey’s timing as an indicator that his announcement should not be considered a serious effort to capture City Hall.

“There are six weeks until petitions go out, and he has no money, no organization, no nothing,” Mr. Sheinkopf said.

“He’s got to be kidding. This can’t be serious,” the consultant added.

If Mr. Kerrey has no intention of mounting a serious challenge to Mr. Bloomberg – of whom, until yesterday, he was believed to be a supporter – his comments might have been intended as a message to Democratic powerbrokers that Mr. Kerrey is interested in re-entering politics, this time as a New Yorker.

“I think it could be that he’s signaling an interest in being involved in New York politics, to look at future openings in New York State,” another Democratic consultant, Evan Stavisky, said. “It may be sort of a head fake, an attempt to say, ‘Don’t forget about me: I’m a former U.S. senator living in New York; think about me as someone in the future.’ “

In addition to revealing his own political ambitions, Mr. Kerrey’s announcement may attest to the inadequacy of the current field of Democratic candidates, consultants said.

A professor of political science at Baruch College, Douglas Muzzio, said party leaders and voters were aware that “this field is not turning on the Democratic base.” A former Bronx borough president, Fernando Ferrer; the Manhattan borough president, C. Virginia Fields; the speaker of the City Council, Gifford Miller, and a Brooklyn-Queens congressman, Anthony Weiner, have been dubbed “the Drab Four” by some of those who follow the race, Mr. Muzzio said, adding that Mr. Kerrey may have therefore viewed himself as a candidate able to inject some needed vitality into the mayoral contest.

“Particularly with the Ferrer candidacy at least stalled, he may have seen that there was an opportunity there, both for him personally, and maybe for the Democrats,” Mr. Muzzio said of Mr. Kerrey, referring to the troubles that have plagued Mr. Ferrer’s campaign following the candidate’s unpopular comments about the Amadou Diallo shooting.

Because of Mr. Kerrey’s background – as a decorated veteran of the Vietnam War, governor of Nebraska, senator, presidential candidate, and member of the 9/11 commission – he is considered a Democratic figure with “gravitas,” Mr. Muzzio said.

As such, Mr. Kerrey’s evident dissatisfaction with Ms. Fields and Messrs. Ferrer, Miller, and Weiner “shows how Democrats of stature feel about the Democrats who are now running for mayor,” Mr. Sheinkopf said, describing the focus on Mr. Kerrey as a “slap in the face” to Mr. Bloomberg’s opponents.

Mr. Sheinkopf and other consultants compared the dissatisfaction with the four Democrats currently in the race – and Mr. Kerrey’s announcement – to rumors in the 2001 race that President Clinton would change the dynamic by jumping in as a candidate at the last minute. Then, as now, Mr. Ferrer was a leading contender. He lost to Mark Green, whom Mr. Bloomberg narrowly defeated.

Even if the Democrats’ defeat in 2001 was foretold by the buzz – albeit empty buzz – that surrounded Mr. Clinton, another consultant, Jerry Skurnik, cautioned against reading too much into the Kerrey talk. The perceived weakness of the Democratic field, Mr. Skurnik said, was more a creation of the press than a widespread conviction among the electorate.

“I think there’s this feeling among opinion leaders that ‘Bloomberg’s going to win, woe is me, we could do better,’ ” he said.

“But if the next Marist or Quinnipiac poll comes out and shows two or three of the Democrats still beating Bloomberg, that’ll quiet down some of the feeling that Bloomberg’s unbeatable,” Mr. Skurnik added.

For their part, the Democrats in question sounded unfazed by Mr. Kerrey’s contemplations.

“I agree with Bob Kerrey’s criticism of Mayor Bloomberg, and that’s the reason I’m running. New Yorkers deserve a mayor who understands their daily problems and will fight against the Republicans to do something about it,” Mr. Ferrer said in an e-mail statement.

Spokesmen for Ms. Fields and Mr. Miller emphasized the respect their candidates have for Mr. Kerrey. Ms. Fields’s spokesman, Nicholas Charles, said the Manhattan borough president was in wait-and-see mode about a Kerrey candidacy, and Mr. Miller’s campaign press secretary, Reginald Johnson, said the City Council speaker agreed with Mr. Kerrey’s criticisms of Mr. Bloomberg and “will remain focused on presenting his record and ideas on how he plans to move New York forward.”

A spokesman for Mr. Weiner’s campaign, Anson Kaye, said: “It sounds like Bob Kerrey already has a candidate in the race, from the issues he’s talking about. … That would be Anthony Weiner.”

If the Democratic candidates were at all stung by Mr. Kerrey’s announcement, Mr. Bloomberg, too, stood to be surprised. A few days ago, Mr. Kerrey had reportedly accepted the mayor’s invitation to head “Democrats for Bloomberg.” According to the Times, Mr. Kerrey’s announced potential candidacy was the first indication to the Bloomberg campaign that the former senator had changed his mind about leading the committee.

In response, Mr. Bloomberg’s campaign manager, Kevin Sheekey, said in a statement that Mr. Kerrey had “praised the mayor on his leadership of the most important issues facing the city.”

“If he’s concerned about the Alternative Minimum Tax,” Mr. Sheekey continued, referring to one of Mr. Kerrey’s criticisms of Mr. Bloomberg, “he should try to get his seat back on the Senate Finance Committee.”