When Mayor Michael Bloomberg went to the Bronx this summer to break ground on a shopping center near the new Yankee Stadium, he noted the two projects won’t be completed until 2009, during his final months in office.

Just before dipping a shovel into a ceremonial mound of dirt, the mayor introduced the president of the Bronx, Adolfo Carrion Jr., to say a few words.

“Mr. Mayor, we have three years, four months and 17 days left to finish our work. But who’s counting?” Mr. Carrion said.

The line got a nervous laugh. There is a growing crowd of people ticking off the hours until Mr. Bloomberg’s expiration date, and Mr. Carrion is among them.

The former City Councilman, who also has been a pastor and public school teacher, is one of several City Hall hopefuls already lining up to take the Republican billionaire’s place.

Meanwhile, Mr. Bloomberg and his inner circle are nervously hoping voters will elect a successor to carry out their long-term ambitions in areas like development, school reform and affordable housing.

Along with Mr. Carrion, the other Democrats frequently mentioned for the 2009 free-for-all include William Thompson Jr., the city comptroller with a strong Democratic base, and Anthony Weiner, an energetic U.S. congressman from Brooklyn and Queens who also ran last year. Some would also like the City Council Speaker, Christine Quinn, to make a run.

And there are always wild cards. Mayoral races here tend to attract unlikely candidates and fuel wild speculations — consider past years when Bill Clinton and Bob Kerrey were among the rumored contenders.

Past ballots have featured Kenny Kramer, the inspiration for the oddball “Seinfeld” character, and Bernard Goetz, whose only claim to fame is that he gunned down four youths on a subway train in 1984.

Mr. Bloomberg himself was once dismissed as a political newbie with no chance in a city where Republicans are outnumbered five to one. But the media mogul pulled off his 2001 victory in part by switching parties to avoid the crowded Democratic field.

Observers say the same could happen with a Republican or an independent in 2009. The names most often mentioned in that scenario include the popular police commissioner, Ray Kelly, and Time Warner’s chief executive, Richard Parsons.

As for billionaires, no candidate with a Bloomberg-sized fortune has yet emerged.

“It looks like the list of wannabes is fairly well-stocked with serious potential players,” said pollster Lee Miringoff. “It’s way too early to figure out who has the inside track, but clearly New York City will not be lacking in big-name, credible candidates.”

Mr. Kelly, an ex-Marine who has overseen a continuing citywide crime drop and is widely credited for New York’s counterterrorism overhaul, says “I don’t have the DNA” for politics when asked if he plans to run.

Mr. Parsons also offered a timid denial this week while he was at City Hall to advise the mayor about poverty reduction. The CEO, whose yearly earnings exceed $10.5 million according to Forbes magazine estimates, serves on a panel studying how city government can help New York’s 1.5 million poor.

As reporters chased him down a corridor to ask whether he is contemplating a mayoral bid, Mr. Parsons muttered no and shook his head as he slipped away, saying he was too busy running the media conglomerate.

None of the potential Democratic candidates are announcing candidacies this early either, but many are raising money and jockeying for attention. Mr. Thompson, the comptroller, churns out audit after audit and is quick to issue statements on the headline of the moment, like gay marriage or fighting in the Middle East.

Mr. Weiner displays a similar urge to weigh in on the news of the day. And the congressman, who nearly forced a runoff in the Democratic primary in last year’s contest, said in an interview this week that he’d still like the job.

Polls show him winning most hypothetical matchups, but Mr. Weiner said his party can no longer rely on their advantage in numbers. Despite its Democratic slant, New York City has elected a Republican four straight terms.

“Party labels are increasingly unimportant to voters, particularly in municipal elections in New York, and we need to understand that,” Mr. Weiner said. “Voters are becoming less and less influenced by party labels and more and more influenced by candidates who excite their sense that they understand the challenges facing regular New Yorkers.”

Mr. Bloomberg hasn’t said publicly who he wants to take over, but many say his deputy mayor for economic development, Dan Doctoroff, would ensure a smooth transition for the projects Mr. Bloomberg has begun.The wealthy former investment banker — who like his billionaire boss, eschews a city salary and earns $1 a year — also insists he’s not interested.

But as the mayor once pointed out after denying for the hundredth time the rumor that he plans to enter the 2008 race for president, anyone who’s running will say exactly that.