ALBANY – Accusing Alfonse D’Amato of putting his business interests ahead of his political principles, Republican gubernatorial candidate William Weld said the U.S. senator turned lobbyist is raising money for the leading Democratic candidate, Eliot Spitzer, and will endorse him for governor.

Mr. Weld, a former governor of Massachusetts, suggested yesterday that by supporting the Democratic front-runner, Mr. D’Amato would be acting in the interests of his high-powered lobbying firm, Park Strategies.

Mr. Weld said he has thought “for some time” that Mr. D’Amato, who served in the Senate as a Republican, would back the state attorney general in the governor’s race. “I thought Senator D’Amato had been raising money for Spitzer for most of the last year. That’s not a surprise to me. That’s business, business, business. That’s not a political decision. That’s a business decision,” he said.

Messrs. Weld and D’Amato have long had a strained relationship, with the latter accusing the Republican candidate of playing a role in the U.S. Justice Department’s prosecution of his brother, Armand D’Amato, who in 1993 was convicted on seven counts of mail fraud in connection with payments he received from a military contractor to lobby his brother. An appeals court later overturned the conviction. Mr. Weld, who ran the Justice Department’s criminal division in the 1980s, has denied that he was involved in the investigation of Mr. D’Amato’s brother.

Mr. Weld did not elaborate on what he described as Mr. D’Amato’s fundraising efforts for the attorney general. Mr. D’Amato has described Mr. Spitzer as a “great attorney general,” and his brother has donated $1,000 to Mr. Spitzer’s campaign. Mr. D’Amato’s former chief of staff, John Zagame, has reportedly been listed as a sponsor of two fund-raisers for Mr. Spitzer.

Mr. Weld’s view that Mr. D’Amato’s apparent support for Mr. Spitzer is simply a matter of business is one that is shared by some Republican leaders in the state. Republicans interviewed said Mr. D’Amato is betting that Mr. Spitzer, who is leading in the polls, is going to be New York’s next governor and he wants to ensure that his firm has access to the next administration.

Mr. D’Amato’s company, which he started after losing to Senator Schumer in 1998, is one of the highest-paid lobbying firms in the state, representing such clients as Verizon, Concerned Home Care Providers, and Madison Square Garden.

“That’s the problem with lobbyists in Albany,” the Republican chairman of Onondaga County, Bob Smith, said. “Too many things become a business decision instead of principle and doing the right thing. That’s the culture in Albany of pay to play. Mr. Weld is probably right to some degree.”

Still, he said he would be “surprised” if Mr. D’Amato endorses Mr. Spitzer, saying it would be a “disappointing” if the former senator backed a Democratic candidate after “injecting himself into the nomination process.”

In recent months, Mr. D’Amato has publicly expressed preferences about whom Republicans should and should not nominate for governor and attorney general. In the attorney general’s race, he has been highly critical of the state Republican Party’s decision to endorse Jeanine Pirro. He unsuccessfully wooed Staten Island’s district attorney, Daniel Donovan, who said he won’t oppose Ms. Pirro in a primary.

Others said Mr. D’Amato’s willingness to cross party lines in his endorsement speaks to the lack of differences between the two sides. “As long as we have a leadership in the Republican Party that doesn’t seriously differentiate itself from the Democrats on vital issues, then people are just going to make business decisions as to who is going to get elected,” said Leo Kayser, an attorney and Republican activist who supports Randy Daniels for governor.

Mr. D’Amato did not return calls for comment.

Mr. Weld made his comments during a visit here, where he met with the Republican majority leader, Joseph Bruno, and other lawmakers. Speaking to reporters, Mr. Weld said he supports tuition tax credits and that he wished the Senate proposed them in its budget, instead of a child tax credit that is not linked to private school tuition. He also said he is hoping that his Republican rival, John Faso, runs for lieutenant governor as his running mate and he said he plans to meet with Democratic candidate Thomas Suozzi to “sit down and compare notes.”

Mr. Faso, a former assemblyman from upstate New York who is vying for the Republican and Conservative Party endorsements, has said he won’ run for any office other than governor.