"This is the first time in history a first lady has run," the former candidate for the Republican presidential nomination told students at Columbia University. "She would be a star of the quality that has not been seen in the Senate since Bobby Kennedy was elected senator from the state of New York.

"Many of us believe that in a scenario if (Vice President Al) Gore lost and she is elected to the Senate, she'd be running for the president of the United States," McCain said.

Clinton has said that if elected she will serve her full six-year term and that she is not interested in the presidency.

Asked to clarify his remarks about Clinton, McCain said, "I believe she'd be very liberal and I don't believe she'd be good for the country."

A day earlier, McCain campaigned in New York City for Clinton's Republican rival for the Senate seat, Mayor Rudolph Giuliani.

He told the students Giuliani would bring "credentials to the Senate that are much needed and very sadly lacking. Giuliani understands the challenges of a major city" on issues like crime and transportation, he said.

But McCain also made a joking reference to his and Giuliani's reputations for belligerence, saying: "I'm sure he and I would be vying for Miss Congeniality."

Asked by a student about Giuliani's handling of the police killing of an unarmed black man, Patrick Dorismond, McCain said: "I believe Mayor Giuliani will be committed to reconciliation and harmony here in the city. In your view and others, he probably has not done well enough because I have heard similar comments to yours. But I hope he will in the future repair that situation."

But McCain also credited Giuliani with turning the city around. "When I came to the city 10 years ago I couldn't walk in the street," he said. "I couldn't go into Central Park. I couldn't even ride in a cab without fear of somebody jerking open the door and yanking me out."