Mayor Bloomberg may have brought the polish of a well-run Wall Street operation to City Hall, but if a visit to the supermarket mogul John Catsimatidis’s office is any indication, the latest billionaire to set his sights on the mayoralty will bring store circulars — and lots of them.

Mr. Catsimatidis, 59, the rotund, red-faced billionaire who switched his party affiliation to Republican from Democrat in anticipation of a likely mayoral campaign, uses ads promoting his grocery store chain, Gristedes, as wall hangings in his dingy waiting room and in the hallway leading to his office.

They may be an odd choice for a decoration, but they are central to any campaign Mr. Catsimatidis may launch. Nearly all Gristedes advertisements feature his photograph, and they have helped him become known, by face at least, to New Yorkers across the city.

Now, with the help of the Republican political operative Robert Ryan, Mr. Catsimatidis is trying to build on that groundwork by sharing and promoting his life story — that of a Greek-born, Harlem-raised, self-made billionaire — in advance of a potential bid for City Hall in 2009.

“Mike Bloomberg is Wall Street and John is Main Street,” Mr. Ryan said, repeating a line that could become a refrain in the coming year. “He came up in the streets of this city and he understands, he understands, why the Korean greengrocer is here, why the cab driver from India is here, why the guy from Central America is here or Africa or the Caribbean. He understands them. And their dreams are his dreams because he has lived them.”

Mr. Catsimatidis, who was ranked in the 220 slot on the Forbes 400 list with a net worth of $2.1 billion amassed from supermarkets, oil investments, and real estate, also understands the needs of the city’s Fortune 500 CEOs, Mr. Ryan added.

“I can have dinner at the diner in Astoria or I can have dinner at the White House,” Mr. Catsimatidis, the chairman and CEO of the Red Apple Group, said, sitting to the left of his adviser at a long table at his company’s headquarters in Manhattan. “To me, it’s irrelative. I’m comfortable in both worlds.”

Mr. Catsimatidis, who has given to candidates from both major parties and has raised money for Senator Clinton, is not exaggerating.

The walls of his cluttered office on 11th Avenue and 56th Street are covered with photographs of himself with some of the nation’s political giants. In one corner, there’s a picture of his wife dancing with President Clinton just above snapshots of himself with Fidel Castro during a trip to Cuba. His dress shirt is secured at the wrists with White House cuff links given to him by President Reagan.

Turn the conversation to the would-be candidate’s policy positions, however, and it becomes clear Mr. Catsimatidis’s stances on issues facing the city are not as fine-tuned as the story line of his life in New York and the image of him as an everyman New Yorker who happens to hobnob with some of the most influential Americans in politics.

When asked about member items in the City Council, for instance, which allow elected officials to direct taxpayer dollars to local organizations of their own choosing, Mr. Catsimatidis seemed to be hazy on where he stands. The member items have come under attack in recent weeks from the editorial pages of the city’s leading daily newspapers and from Rep. Anthony Weiner, a mayoral candidate, who has called for an end to them.

“I think it’s very, very sad that everyone has a slush fund,” he said. “And I think it’s sad that they divvy out the money to only people who donate to them. So it’s almost like a quid pro quo.”

He said he’s not advocating in favor of member items, but said he doesn’t think they should be banished either. The city should take care of its nonprofits, he said, but make sure there isn’t a kickback for council members, without offering specifics.

When asked about charter schools, he said the city needs schools “where people are not scared that their kid is going to go to the school and get mugged, knifed, etcetera, etcetera.”

“I promote charter schools, because if we can have a better system, I guess — How many do we have now?” he said, trailing off. He later added: “I think it’s a great experiment or whatever you want to call it. And if it works, it works.”

Mr. Ryan emphasized that Mr. Catsimatidis is not yet running for office and would be defining his stance in a number of areas as he moved forward.

On other policy questions, however, Mr. Catsimatidis offered a clear opinion, stating that he believes marriage is meant to be between a man and a woman, and that he supports Mr. Bloomberg’s ban on trans fats in restaurant food.

He said taxes should only be raised if there is a built-in expiration date so the increases automatically sunset, and suggested the city’s congestion problems might be alleviated if more traffic officers were hired to keep traffic moving on side streets and prevent double parking.

Mr. Catsimatidis declined to state his stance on abortion.

One visible and immediate imprint Mr. Catsimatidis could make on the city, if elected mayor, would be in the city’s bars. An occasional cigar smoker, he said he’s in favor of increasing the number of licenses awarded to bars to allow smoking, so long as employees signed a waiver agreeing to the workplace smoke.

At the end of the day, his campaign may all come down to money: his and the taxpayers’.

“What I’m going to say to taxpayers is, ‘Who do you want watching your money?'” he said. “I can’t fix what was done 10 years ago or 20 years ago, but under my watch, I’m going to be watching your money and taxpayers are going to get a good deal.”