New York's top elected Republican tried to patch over one of America's most bitter party feuds yesterday, calling for unified support behind New York Mayor Rudolph W. Giuliani to face first lady Hillary Rodham Clinton in her likely bid for the Senate.

Gov. George E. Pataki said in a statement that "it is critically important to our future that we have a unified party and elect a Republican senator in the year 2000." He also said: "I believe that Rudy Giuliani has earned the right to be [the] candidate."

The statement is a striking measure of the Republican desire to defeat Clinton, there being no love lost between Pataki and Giuliani. The blood is even worse between Giuliani and former senator Alfonse M. D'Amato, who is a patron of Pataki and remains one of the leading forces in the New York GOP.

In backing Giuliani, the governor attempted to deflate the Senate hopes of Rep. Rick Lazio, a Long Island Republican and D'Amato protege. "I predict great things for" Lazio, Pataki said, even as he called on the congressman to defer his ambition.

But a source close to Lazio suggested that the congressman will not cooperate. "He's in," the source said. "He's running."

Pataki's statement followed weeks of discussion between the governor's staff and the mayor's people, as well as with D'Amato. National Republican leaders have put pressure on Pataki to prevent a nasty Republican primary that would drain away resources and bloody their nominee while Clinton sails along unchallenged on the Democratic side.

The mayor had his own statement yesterday: "I very much appreciate Gov. George Pataki's strong words of support. Under his leadership and the leadership of state [GOP] chairman Bill Powers, the Republican Party is surely going to be unified in the effort to elect a senator from New York."

Though Giuliani has not officially entered the race, he has been acting like a candidate for months. Recently, he traveled to Arkansas for a fund-raiser as a way of mocking Clinton for planning to run in a state where she has never lived.

Lazio, meanwhile, has piled up $3 million for the race--more than Giuliani has on hand for a campaign that is expected to cost as much as $25 million. When Lazio set Aug. 16 as the date for his campaign kickoff, Pataki decided he had to move quickly to choose a candidate.

According to a source close to Giuliani, Pataki arranged a meeting earlier this week between Giuliani and D'Amato at Gracie Mansion, the official residence of the New York mayor. The two men once were friendly enough; D'Amato backed Giuliani years ago for the career-launching position of U.S. attorney in Manhattan and Brooklyn. The two appeared together--dressed in body armor on a drug raid--in what became one of the most laughed-over pictures in the city's political history.

But somewhere along the way they became enemies. In 1994, Giuliani endorsed Democratic Gov. Mario M. Cuomo for reelection rather than support Pataki--who was then a fairly obscure state politician known only for his D'Amato ties. Pataki won, and Giuliani was in the doghouse.

At the Gracie Mansion meeting, D'Amato lectured Giuliani on the importance of team play and deference to his fellow Republicans--two traits that have never been among the mayor's strengths. "The overwhelming subject was r-e-s-p-e-c-t," said a Giuliani confidant. "He told Rudy he needs to be more respectful of the governor." After that, the source said, D'Amato gave the green light to Giuliani.

Kieran Mahoney, a GOP strategist in New York, explained why: "The mayor represents close to 8 million people in New York. He is better-known throughout the state. Do you go into a pennant drive with a proven major leaguer or a promising rookie? Giuliani is a proven major leaguer."

Leading Republicans around the country--some of whom have been muttering in recent weeks that Pataki would destroy his career if he failed to unify the party--praised the governor's choice.

"This clears away our biggest concern in New York, which was the possibility that we would have a strongly contested Republican primary," said Sen. Mitch McConnell (Ky.), chairman of the National Republican Senatorial Committee. Former party chairman Haley Barbour said: "Governor Pataki has exhibited the strong leadership he is becoming known for."

Pataki stopped short of endorsing Giuliani. Instead, he urged the mayor to make a quick announcement of his intentions. If he is running, Pataki said, Republicans should give him their support.

Lazio's offices in Washington and New York offered no comment on Pataki's statement, even though the governor said he had spoken with Lazio to ask that he take no action until Giuliani makes it official. There was just the cryptic statement from someone who would agree only to be identified as a Lazio campaign source: "He's in it. He's running."

McConnell seemed unconcerned about Lazio now that Pataki is preaching peace. "Obviously, he's free to do whatever he wants," McConnell said of the congressman. "In the end, this is going to be decided by New York Republicans, and I think this action by the leading figure in the party in that state will go a long way toward deciding this."

New York is known for its Byzantine ballot and election rules, which sometimes amplify the effect of smaller parties in close races. The state's Conservative Party has its own line on the ballot and can boost the GOP by listing the Republican nominee. Or the conservatives can zing Republicans by choosing their own candidate--Lazio, for example.

Conservative Party Chairman Mike Long said yesterday that Pataki's decision "doesn't have any effect on me or my party. We will continue to talk to candidates who want to pursue the principles we seek to advance." The conservatives have never endorsed Giuliani in his mayoral campaigns, Long said, but he added that he feels "Giuliani has done an outstanding job as mayor of New York."

Hillary Clinton was in Rochester, another stop on her "listening tour" of the state, when Pataki made his move. Her audience seemed to have little interest in the two media obsessions surrounding the first lady--her recent remarks on her husband's infidelities, and the fact that her step-grandfather turns out to have been Jewish. (Headline in the New York Post: "Oy Vey!")

"I don't think it serves our nation or our political process well for people to have every shred of their privacy taken away from them. . . . I'm speaking as someone who's been through it," Clinton said to enthusiastic applause.

She said nothing about Pataki. And when a reporter asked how she plans to defeat Giuliani, Clinton said: "Oh, I'm not in a campaign yet." Her listening tour, she said, will continue well into the autumn.

Clinton spokesman Howard Wolfson said, "What the Republicans do or don't do is up to them. Mrs. Clinton is going to continue focusing on issues and listening to New Yorkers."

Staff writer Lynne Duke in New York contributed to this report.

CAPTION: In rising above a bitter party feud and calling for Republican unity in New York's Senate race, Gov. George E. Pataki, left, said of the New York mayor, right: "I believe that Rudy Giuliani has earned the right to be [the] candidate."