New York City – Invisible Mayoral Candidate William Thompson

New York City – He is rarely on television. He has not begun to advertise. He is far behind in the polls, yet seems in no rush to get going.

The all-but-invisible mayoral candidacy of William C. Thompson Jr., the city’s comptroller, is baffling even to those who wish to see him elected. He has raised $5 million but has been so low key, some Democrats wonder if he is actually running.

And often, when Mr. Thompson travels, he hears the same question: Where have you been?

The incumbent, Mayor Michael R. Bloomberg, is everywhere: on television, with a $12 million barrage of ads touting his re-election bid; in mailboxes, with a constant stream of glossy literature; and online, with ads popping up on Web sites from Facebook to local blogs.

A woman approached Mr. Thompson in the Bronx not long ago and asked if she would be receiving campaign literature from him.

“Not anytime soon,” he said.

The comptroller, a mild-mannered, wonkish and careful politician, said he had no choice but to hold back. The only way he can defeat Mr. Bloomberg, he said, is to bite his lip for several months, conserve his campaign money and deliver a last-minute assault in the fall.

But concern inside Democratic circles about Mr. Thompson’s retiring style is taking on new urgency, given Mr. Bloomberg’s success in unveiling endorsements almost every day from a wide range of groups, including from several prominent Democratic elected officials and groups traditionally aligned with Democrats, like Naral Pro-Choice New York and the New York League of Conservation Voters.

And some worry that Mr. Thompson’s approach is less a function of strategy than a lack of drive and energy.

Either way, his approach is the political equivalent of trying a rope-a-dope for 14 rounds and hoping to land a knockout in the 15th.

“To try to go toe to toe with the mayor makes no sense,” he said during a recent interview at a downtown restaurant. “There is no way we can compete on TV and radio.”

Mr. Thompson is taking a cheaper, grass-roots approach, visiting three to four union halls and neighborhood Democratic clubs a night and testing messages that his aides hope will build a loyal following and erode support for the mayor.

In a stump speech he can recite from memory, he attacks the mayor as an out-of-touch, Manhattan-centric billionaire whose policies have protected the wealthy and ignored the middle class.

In what passes for a rousing punch line, he claims that Mr. Bloomberg sandbagged voters by tearing up the city’s term-limits law, which allowed him to seek a third term. Mr. Thompson calls it “the day democracy died in New York.”

In general, the crowds are small — often fewer than 30 people — and the applause is tepid. Even news conferences sometimes veer off the script. On Tuesday, as he was garnering the endorsement of a Chinatown civic organization, a would-be supporter blurted: “The Puerto Rican people behind you! Don’t worry!” followed by a vulgarity aimed at the mayor.

Mr. Thompson cringed, and said: “O.K., we’re on camera. Why does this always happen to me?”

Outside political circles, most people do not even know who he is. In a recent poll taken by The New York Times, Cornell University and NY1 News, almost three-quarters of respondents said they did not know enough about Mr. Thompson to form an opinion.

To some degree, Mr. Thompson has been overshadowed by the turmoil in the State Senate in Albany. But he has also failed to seize on a signature issue or define himself in a way that has grabbed the public, Democrats complain privately.

Mr. Thompson’s aides say that a Bloomberg victory is far from inevitable and that New Yorkers are jittery about the economy, rising taxes and the school system.

Indeed, the recent poll suggests that Mr. Bloomberg has vulnerabilities. While most New Yorkers still approve of the job he has done, he is hardly beloved, and is skewered by critics as an imperious tone-deaf billionaire who cares mostly about people with money. A majority of people in the recent survey said that they disapproved of Mr. Bloomberg’s successful effort to change the city’s term limits law last fall and that they would like to give someone else a chance as mayor.

By November, Mr. Thompson’s supporters believe, voters may be ready for a new occupant at City Hall. The challenge is to convince them that Mr. Thompson should be that somebody else, even as the mayor outspends him by a rate of nine to one.

At times, Mr. Thompson gets frustrated by the lopsided financial fight.

A couple of months ago, he stormed into a strategy session at his campaign headquarters in Lower Manhattan. He had seen the latest Bloomberg television commercial, and demanded that his aides produce a matching ad, said a person who was in the room.

Stunned aides furiously scribbled down his instructions. But a few minutes into his tirade, Mr. Thompson cut himself off.

“We can’t take the bait,” he told the aides, and called off the plans.

Even without TV advertising, Mr. Thompson is having a hard time curbing his spending, burning through his campaign money at a faster rate than the last Democrat to lose to Mr. Bloomberg: Fernando Ferrer.

Unlike Mr. Ferrer, however, Mr. Thompson may have the luxury of a stress-free — and relatively cheap — primary in September. His strongest potential rival, Representative Anthony D. Weiner, announced in late May that he would not run for mayor. That leaves City Councilman Tony Avella, an outspoken and colorful Queens Democrat, who has raised less than $250,000 so far and remains a long shot for the nomination.

That gives Mr. Thompson months to introduce himself to New Yorkers and, crucially, raise money.

Mr. Thompson is finding inspiration in the mayoral campaign of Michael Nutter of Philadelphia, who was hailed as the Seabiscuit of Pennsylvania politics for staging an unexpected, last-minute victory in the Democratic primary in 2007.

Mr. Nutter’s profile, like Mr. Thompson’s, was that of an uncharismatic, by-the-book politician. And like Mr. Thompson, Mr. Nutter was a decided underdog in a contest that included a billionaire businessman.

So Mr. Thompson has hired two people who worked on the Nutter campaign: Geoffrey D. Garin, a pollster with the Garin-Hart-Yang Research Group; and Doc Sweitzer, a political consultant from the Campaign Group. If it can happen in Philadelphia, Mr. Thompson’s thinking goes, then why not in New York?

“Little by little, Nutter peaked at the right time,” he said.