New York Republicans yesterday gave a frosty reception to their newest member, Thomas Golisano, a self-made billionaire from Rochester who bitterly campaigned against Governor Pataki in three unsuccessful gubernatorial bids.

Mr. Golisano, 63, yesterday announced that he had abandoned the Independence Party, which he co founded, to become a Republican and was “seriously considering” running for governor once again. Some Republican officials viewed his move with suspicion and raised questions about whether a man who prides himself on his political independence could find a home in the state GOP.

Questions immediately surfaced about donations Mr. Golisano made to two 2004 Democratic presidential candidates and money that his Fortune 500 payroll-processing firm gave to a Democratic state party committee.

Mr. Golisano gave $2,000 to Democratic primary candidate Richard Gephardt in September 2003 and $2,000 to Democratic presidential nominee Senator Kerry in February 2004, the only donations he made to the presidential campaigns, according to records from the Federal Election Commission. The company that he founded, Paychex, has contributed almost $5,000 to the New York Democratic Senate Campaign Committee.

Those contributions, along with Mr. Golisano’s caustic attacks on the leadership of the state Republican Party during his gubernatorial campaigns, were viewed by some Republicans as signs of irreconcilable differences between the party and the potential candidate.

“It’s going to be a hurdle for him to come back and say, ‘I can be your guy,’ when he’s never shown any affinity to the ideology prior to this,” a Republican state senator from Long Island, Michael Balboni, said. “One has to ask the question of why is he joining the Republican Party. Is it because it’s the only game in town?”

That criticism was echoed by a senior adviser to a Republican candidate for governor, Randy Daniels, the former New York secretary of state. “Over the past decade, Tom Golisano has spent tens of millions of dollars attacking Republican policies and Republican candidates,” the adviser to Mr. Daniels, Robert Ryan, said. “Now, he wants to become a Republican?”

A close adviser to Mr. Golisano, Laureen Oliver, who co-founded the Independence Party of New York with the billionaire in 1994, cautioned that he “doesn’t attach politics to everything he does.”

“He will be the same Tom Golisano who ran in 2002, 1998, and 1994,” she said. “A piece of paper is not going to change that.”

In a statement released yesterday, Mr. Golisano said his decision to change parties was heavily influenced by a conversation he had with Senator McCain, who convinced him “that I could be a more effective advocate for reform as a Republican.”

Mr. Golisano said in the statement that the state must get taxes, spending, and borrowing “under control,” “root out the billions of dollars of fraud in our Medicaid system,” and “strive to make our public schools the best in the nation.” He also noted that he was following in the footsteps of prominent politicians who switched parties, citing the examples of Ronald Reagan, Mayor Giuliani, and Mayor Bloomberg.

As a Republican, Mr. Golisano, who owns the Buffalo Sabres professional hockey team, brings to the party a long record of spending his personal wealth on political causes, heralded management skills, and business acumen. His company Paychex, which he founded in 1971 with $3,000 in start-up capital, is one of the great American business success stories and now boasts more than 500,000 clients. Washington Post columnist George Will once called Mr. Golisano “a Ross Perot without the weirdness.”

Mr. Golisano also has greater name recognition than the other Republican candidates – largely a result of his three bids for office – and some say the potential to help the party secure its majority in the Senate by drawing enough Republican voters to the polls who would vote down-ticket for other party candidates. As a third-party candidate, Mr. Golisano received 14% of the vote in the 2002 race after spending $75 million of his fortune on his campaign. He performed worse in the 1994 and 1998 campaigns.

Those advantages are tempting for one of the state’s most powerful Republicans, the Senate majority leader, Joseph Bruno, who has met with Mr. Golisano to discuss the billionaire’s political ambitions in recent weeks. In a statement yesterday, Mr. Bruno congratulated Mr. Golisano for “becoming the newest member of the New York State Republican Party.”

A declared Democratic candidate for governor, the state attorney general, Eliot Spitzer, is polling far ahead of other Republican candidates, who include Mr. Daniels; a former state Assemblyman, John Faso, and William Weld, a New York native who was elected governor of Massachusetts in 1990 and 1994.

Some Republicans are wary of a primary battle that could pit Mr. Golisano against Mr. Weld, who is favored by the chairman of the New York Republican State Committee, Stephen Minarik. Mr. Weld has a reputation of being a Republican moderate who cut taxes as governor and has taken liberal positions on social issues such as gay rights and abortion.

If Mr. Golisano runs and does not receive the endorsement of the Conservative Party of New York State, which has 170,000 members, the Republican Party could see party members stay home or defect to the Conservative Party. As the Conservative Party leadership likes to point out, no Republican running for statewide office has won an election without the party’s endorsement since 1974,when Jacob Javits was re-elected to the U.S. Senate.

The chairman of the Conservative Party, Michael Long, told The New York Sun yesterday that Mr. Golisano called him, informing him that he had switched parties and that his registration change “didn’t necessarily mean a run for the governorship.” Mr. Long said Mr. Golisano asked if they “could get together at some later date and have a discussion,” and Mr. Long agreed.

Mr. Long said his party has not settled on any candidate and that he would go into the meeting with an open mind. He said, however, that the donations Mr. Golisano made to Mr. Gephardt and Mr. Kerry do not “help any candidate if in fact one is serious about being a Republican candidate.”

Mr. Minarik gave mixed signals yesterday about Mr. Golisano’s party registration change. “Our great party encompasses what each and every American wholeheartedly believes in, which are the right to individual freedom, lower taxes, reducing the size of government, and true reform,” Mr. Minarik said in a prepared statement. “Tom Golisano’s statement echoes many of those beliefs,” he said.

To the Associated Press, Mr. Minarik expressed concern about Mr. Golisano’s past criticisms of Mr. Pataki. “I don’t know how you overcome that. The party is still Governor Pataki’s party … It’s awkward at best,” he was quoted as saying.

The AP quoted Mr. Pataki himself as saying only, “I am always in favor of the Republican Party having more people enrolled in it.”