As the city comptroller for the last five years, William Thompson Jr. is well positioned to replace the dethroned state comptroller, Alan Hevesi. Mr. Thompson, like Hevesi, has overseen a multibillion-dollar pension fund for public employees and served as a watchdog for a big government budget.

But Mr. Thompson says he doesn’t want the job.

By rejecting the chance for a four-year statewide post that comes with substantial power and fund-raising opportunities, Mr. Thompson is sending an unmistakable signal to supporters and rivals alike that he is serious about making a run for mayor in 2009.

Some political analysts say Mr. Thompson, a Democrat, is making the right move for someone in his position. “Why would you go for a second-rate job when you could go for a first-rate job?” a political consultant, Norman Adler, said.

The decision is not without risk, however. Mr. Thompson has positioned himself as an early front-runner for the Democratic nomination in 2009, but he is likely to face stiff competition from the Bronx president, Adolfo Carrion Jr., and Rep. Anthony Weiner, who nearly forced a primary runoff with Fernando Ferrer last year. He could also face the chairman of Time Warner, Richard Parsons, or Mayor Bloomberg’s police commissioner, Raymond Kelly, either of whom could be formidable candidates.

“He’s got citywide experience, and he’s got an unsullied record in the comptroller’s office,” Mr. Adler said of Mr. Thompson, adding that the city comptroller is well liked by Democrats. The comptroller also has more than half a million dollars in his city campaign account, according to the most recent public filings, a number that will rise significantly when the next filing is due in January.

For Mr. Thompson, a former president of the now-defunct Board of Education, a mayoral run would be easier from the five boroughs, where he would have a hand in city policy.

“The road to City Hall is not paved through Albany,” a political consultant who has advised Mr. Thompson, Hank Sheinkopf, said. He noted that, as an African American, Mr. Thompson has a large voter base, and he is the only Democratic hopeful to have won citywide office — twice.

As state comptroller, Mr. Thompson would be “in the backwater,” a public affairs professor at Baruch College, Douglas Muzzio, said. “He’s in Albany. He’s not where the action is.”

Speaking to reporters last week, Mr. Thompson said he was “not interested” in the state job. He was not one of several potential candidates to contact the Assembly speaker, Sheldon Silver, in the days since Hevesi resigned in a plea deal on Friday, the speaker’s office said yesterday.

The full state Legislature, where Democrats have a majority, will vote on the next comptroller, whom Mr. Silver will likely select in consultation with Governor-elect Spitzer.

Mr. Silver told the Associated Press yesterday that several contenders had reached out to his office over the weekend, including Assemblymen Richard Brodsky of Westchester, Thomas DiNapoli of Long Island, Joseph Morelle of Rochester, and Alexander “Pete” Grannis of Manhattan. He also heard from the comptrollers of Buffalo and Nassau County, as well as William Mulrow, a businessman who lost to Hevesi in the 2002 Democratic primary.

Mr. Carrion, who emerged as a contender last week, also contacted Mr. Silver, the speaker’s office said. Mr. Silver told the AP that the Assembly would interview candidates in public hearings and that a new comptroller would likely be chosen by the end of January.

Even if he put himself in the running for the state job, Mr. Thompson’s selection would be far from assured. Mr. Thompson’s experience managing the city’s pension fund appears to make him plenty qualified – Hevesi also served as city comptroller before his election to the state post. But Messrs. Spitzer and Silver may want to pick someone from outside the five boroughs to balance an Albany leadership that is heavy on officials with roots in New York City.

A move to Albany for either Mr. Thompson or Mr. Carrion would shuffle the 2009 deck by removing a top Democratic contender from the field. The two could end up battling for overlapping blocs of black and Latino voters. “Nobody in the Democratic Party is really looking forward to the Carrion-Thompson primary,” the dean of Baruch College’s School of Public Affairs, David Birdsell, said. “That has the potential to be an enormously divisive primary.”

Hevesi stepped down on Friday in connection with a guilty plea for using a state driver to chauffeur his ailing wife for three-and-a-half years. He was re-elected last month, and his second term would have begun January 1.