"I haven't heard one voice speak out against the president's pick for the Supreme Court except for one person, and that's Michael Bloomberg."

Two things are interesting here: the source of the comment, and the target. The speaker is Michael Long, chairman of the New York State Conservative Party, which is closely allied to President Bush.

Long's target is the Republican mayor of New York City. Well, sort of. Appearing Sunday on WNBC's "News Forum," Long called Bloomberg a "Republican in convenience only."

"This is what happens to a political party when you let the fox in the chicken coop," the conservative leader fumed. "Okay, and a fox who is well-heeled, a fox who has a lot of ammunition and can do an awful lot of things with the wealth he has."

The foxy Bloomberg does, indeed, have a lot of ammunition. A poll last week by Quinnipiac University put the mayor's approval rating at 60 percent, and he led his closest Democratic rival, former Bronx borough president Fernando Ferrer, 52 to 36 percent. Call him a nominal Republican, a counterfeit Republican or an ersatz Republican, Bloomberg is still a Republican in one of the most Democratic cities in the nation. If he wins a second term, the city of Tammany Hall and Al Smith will have spent 16 years under Republican mayors -- Bloomberg's two terms added to Rudy Giuliani's two before that.

New York City, which voted for John Kerry over George Bush by better than 3 to 1, is not seceding from blue America. But it has a habit of electing unusual Republican mayors in unusual circumstances.

Giuliani was narrowly elected in 1993 because New Yorkers sensed that their city was in deep crisis. He was reelected handily four years later because he kept his core promise to restore order and confidence to a city that had been short on both.

You have to go back to 1965 and John V. Lindsay to find another Republican winner. If Giuliani was the closest thing to a conservative mayor that New York has had in modern times, Lindsay was one of the country's most liberal mayors, period. Lindsay won because the Democrats had run out of energy. "He is fresh and everyone else is tired," the peerless columnist Murray Kempton wrote 40 years ago. Unfortunately for Lindsay, New Yorkers, especially those living outside of Manhattan, grew tired of him and liberalism.

Lindsay eventually switched to the Democratic Party, but Bloomberg, in order to become mayor, switched the other way. The GOP had no plausible candidate in 2001, when Giuliani, at the height of his popularity after the World Trade Center attacks, was forced out by term limits.

Bloomberg is, roughly, 40 percent Giuliani and 60 percent Lindsay.

"What he represents is that part of Giuliani's legacy that has become permanent, on crime and welfare," says Fred Siegel, author of "Prince of the City," a lively new biography of Giuliani. "But Bloomberg is also a throwback to earlier figures like Lindsay and [former New York governor] Nelson Rockefeller in playing interest group politics." And, like Rockefeller, the billionaire Bloomberg has been unabashed in his generosity to a wide range of New York City charities and social groups. To put it as New Yorkers do: He's bought himself a lot of friends.

And he's been skilled in courting the liberal interest groups. Bloomberg's comment that he would oppose John Roberts if Bush's Supreme Court nominee didn't disclose his position on abortion came shortly after the mayor won the endorsement of NARAL, the abortion rights group. He has won over a slew of unions, including the largest representing city workers. Teachers union president Randi Weingarten echoes Long. "Mike Bloomberg may be a Republican these days," Weingarten told the Daily News. "But he has been a Democrat for most of his adult life."

That has not stopped four Democrats from running as actual Democrats -- frontrunner Ferrer, City Council Speaker Gifford Miller, Manhattan Borough President C. Virginia Fields and Rep. Anthony Weiner of Queens. But if Bloomberg is vulnerable, it may be from the right, not the left, and from disaffection in Queens and Staten Island, not Manhattan. A recent New York Times poll found that liberals view Bloomberg more favorably than conservatives.

No wonder that Bloomberg is trying to have a conservative challenger, former City Council member Thomas V. Ognibene, removed from the Republican primary ballot.

When it's all over, Long may have it exactly right: Bloomberg could well deliver a nominal Republican victory here in November -- at the price of delivering a substantive victory to liberals. Think of him as the bluest red mayor in the country.