Updated

Republican presidential candidate Rudy Giuliani made his 28th appearance on the "Late Show" with David Letterman on Monday, answering hypotheticals about the Iraq war in a friendly exchange with the puckish comedian.

Letterman asked the former New York mayor about the war and its chaotic aftermath.

"I think there would have been a better strategy," Giuliani said. "We kind of didn't plan for that the way we should have."

In response to another question, Giuliani touched upon President Bush's legacy, something that has been hotly debated, with former President Jimmy Carter calling Bush's foreign policy "the worst in history" over the weekend.

"The determination of the kind of president George Bush is will be made by history, and then there'll be big decisions that he made that people are going to look at," Giuliani said. "Harry Truman was, you know, had significant difficulties as great or more than George Bush's but then, in retrospect, when you look back on it, he made the big decisions of his presidency so well that he's become one of our good to great presidents."

Letterman also inquired whether Giuliani gave Democratic presidential candidate Hillary Clinton much thought at night before falling asleep.

"That is not my last thought before I go to sleep at night," Giuliani said. "It could be, it could be Sen. Clinton, it could be Sen. Obama, it could be Sen. Edwards, or, who knows, it could be former Vice President Gore. Who knows?"