Bush turned to the pillars of Republican power in New York in an effort to snuff McCain's insurgent campaign, but there was controversy even there. Mayor Rudolph Giuliani was resisting the McCain-bashing efforts of Gov. George Pataki and other GOP state leaders.

Four days before Republicans vote in 13 states, there were no signs that McCain was closing Bush's wide leads in California, Ohio, Missouri and Georgia polls. New York was competitive and most of New England was leaning McCain's way, but some advisers warned privately the Arizona senator's candidacy was in jeopardy unless he could generate fresh support this weekend.

Both Bush and McCain were ardently seeking the 101 convention delegates at stake in Tuesday's New York election -- second-most to California's 162.

McCain, pummeled in new television commercials, was firing back with a heavy telephone barrage targeting the crucial Catholic vote, fully 46 percent of the state's GOP electorate. McCain aides insisted the appeal was a positive one.

Stirring the most controversy was a Bush commercial arguing that McCain voted against breast cancer research. McCain's allies demanded an apology, noting that McCain's sister -- Sandy McCain Morgan -- has been diagnosed with the disease.

McCain said he has repeatedly voted to increase spending on breast cancer research and the vote cited in the Bush ad was one where he opposed putting breast cancer money in a military spending measure.

Bush rejected the criticism at a cancer research center on Long Island.

Wearing a pink ribbon on his lapel, sitting between a doctor and a breast cancer survivor -- and with former presidential candidate Elizabeth Dole sitting in the front row -- the Texas governor said cancer research was a legitimate use of tax dollars.

"The ad speaks to programs that he called 'garden-variety pork,"' Bush said at a news conference after his session at the Stony Brook Breast Cancer Research Center.

"I don't think the senator should be squealing about pork and then squealing when somebody disagrees with one of the cuts he wants to make. That's what the ad says," Bush added.

Told of the illness suffered by McCain's sister, Bush said: "All the more reason to remind him of what he said about the research that goes on here. I'm sorry if that's the case; that obviously is very difficult for her and her family."

In addition, McCain's environmental record was under fire in a widely run ad purchased by a private group not heard of before in the campaign. McCain contended the effort was coordinated by the Bush campaign, a charge Bush rejected.

"Here's a guy who gave waivers to 85 polluters, all of whom gave to his campaign," said McCain. "Somebody is putting in $2 million to try to hijack the campaign here in New York."

"It's everything I've been fighting against," said McCain. "Two million dollars in the last few days in this campaign can make a difference in a race that is a statistical dead heat."

Texas investor Sam Wyly, a prominent Bush donor and a supporter of his past campaigns, was behind the ad.

Bush said, "There is no connection between my campaign and this ad. We had no knowledge whatsoever that Sam Wyly was going to run this ad. There is no coordination."

New York is one of the biggest prizes at stake Tuesday and the ferocity of the fighting underscored the stakes. Polls have shown Bush with a lead in California and Ohio -- two other "Super Tuesday" prizes -- while New York is close.

McCain's advisers privately concede he's likely to lose California and hope he can offset that with victories in New York, New England and Ohio.

He has repeatedly over-performed his poll ratings by drawing unexpected numbers of independents and moderate Republicans.

McCain's aides were making a heavy effort to court Catholic voters.

In other races, McCain's calls have noted that Bush went to Bob Jones University without quickly renouncing that school's anti-Catholic bias. But the message was different in New York, simply making McCain's economic pitch to a list of likely Catholic voters.

As he campaigned on Wall Street on Friday, McCain was seeking a balance between responding to assaults and sounding his basic campaign themes.

"You can't be diverted," he said. "If I've made mistakes in this campaign it's because I've allowed myself to be diverted."

Despite that, McCain was spending a fair amount of time responding to Bush. Rebutting the environmental accusations, Martha Marks, head of a group called Republicans for Environmental Protection, was at McCain's side praising his record.

"Of the Republican candidates in this primary election, John McCain has by far the best environmental record," she argued.

McCain aides said they'd benefit from a backlash because the ads went over the top.

"The Bush campaign made a colossal mistake with these two ads," said media strategist Mike Murphy. "It the great, late mystery smear."

The New York fight matched the enthusiasm of McCain's insurgents, against the muscle of the GOP establishment, but there were chinks in the establishment armor.

Pataki and Giuliani have both endorsed Bush, but Pataki has been criticizing McCain repeatedly while Giuliani has refused.