In an exclusive interview with ABC News, Republican presidential front-runner Rudy Giuliani said he "made a mistake" by not vetting his former police commissioner, Bernard Kerik, indicted Thursday in a public corruption case. Giuliani also said he wouldn't contribute to Kerik's legal defense fund because it "wouldn't be appropriate."
But Giuliani also said the experience would make him a better president, defended the job Kerik did as police commissioner and compared his former protégé to the late President Richard Nixon -- a man with both flaws and accomplishments.
The former New York mayor said that Kerik's indictment does not sully his mayoral record.
"You have to judge that in the overall context in everything that I did, and how many right decisions did I make and how many wrong decisions did I make," he said. "And the balance is very much in favor of -- I must have been making the right decisions if the city of New York turned around. If crime went down by 60 percent, if homicide went down by 70 percent."
"I made mistakes when I was the mayor, and I make mistakes as a candidate, I will make mistakes as a president," Giuliani said.
"The question is do I make a lot more correct decisions than I make wrong ones? And do I recognize the wrong ones that I make as soon as I can and try to change? And in that particular case, the mistake that I made was I should have checked it more carefully. I didn't and I realized that after it happened, and I admitted it and I apologized for it and I'm never going to do it again. We're going to be much more careful in the future."
As mayor, Giuliani appointed Kerik as his Department of Corrections commissioner in 1998 and his police commissioner in 2000.
Giuliani said Kerik had "problems I should have known about, and had I known about them at the moment I had known about them, I would not have gone ahead with him."
He suggested that the experience with Kerik "makes me better in the sense of being a more realistic executive."
His remarks were part of a larger interview focused on his years as a U.S. attorney for the Southern District of New York -- ironically the same office that brought charges against Kerik -- where Giuliani first achieved widespread notoriety in the 1980s as an aggressive prosecutor pursuing public corruption and mafia-related cases.
Even after faulting himself for not adequately vetting Kerik, the former mayor praised him as "one of the most decorated cops in the police department," an "exceptional" commissioner for the Department of Corrections, and someone who "did the impossible" as police commissioner.
"But, you know, people are complex," Giuliani said. "Richard Nixon had this very serious problem, but his breakthrough with China was one of the historical things that happened in the 20th century. You can't take that away from him."
When asked if that didn't seem to be excusing the crimes Kerik is alleged to have committed -- receiving free apartment renovations and rent from sources trying to curry favor with him, and failing to pay taxes on those gifts -- Giuliani said, "Of course not. How about: It's reality It's the complexity of human life and the reality of human life. And sometimes in political discussion we get very simplistic and we get to yes and no answers."