Paul, for his part, told Leno he was not going to endorse another member of the Republican field any time soon even if he loses the primary in New Hampshire -- a poll released tonight by CNN and WMUR shows Paul tied for fourth place with former New York Mayor Rudy Giuliani at 10 percent support among Republicans in state where "Live Free or Die" is on the license plates.
Paul did mildly defend Mitt Romney, the former Massachusetts governor and Mormon whose support in recent polls seems to be ebbing.
"One thing I'm a little bit afraid of is that they might be doing that for religious reasons, and I don't like that. I disagree with Romney on some of the issues, and he's gone after me on the stage, but that shouldn't be the reason that he doesn't do well."
Some of the biggest applause for Paul came from a dig on former New York Mayor Rudy Giuliani.
"You know, when we had a little confrontation early on in the debates with Mayor Giuliani when he was confused about what causes terrorism I sent him some books. And I said, 'Please read these books.' But so far it doesn't sound like he's read his books. He hasn't done his homework."
Paul told Leno about his belief that the United States bears some responsibility for the terrorist attacks of 9/11. And he argued against the surge in Iraq despite gains in security there.
"But I'm afraid what happened is that we lost the south. The south now is all controlled by the Shiites, and they're aligned with the Iranians. And the British left. So we more or less lost the South, and there's more peace there and less killing. But there's more killing over there. It's still very, very disruptive. I'm scared to death that we're going to be in Pakistan before it's over. And we still haven't taken off the table any option to go into Iran. We don't need that. The American people don't need a bigger war. Besides, we're broke. We don't have any money to afford this anyway."
Leno also asked Paul about the war among the Presidential candidates for the mantle of who represents more "change."
"I think the American people want change," said Paul, who by opposing most federal programs is arguably the candidate of most change. "So everybody gets up and says, 'I'm for change. I'm for change.' But the whole thing is, is what kind of change? You know, right now whether you like Republicans or Democrats, does foreign policy change? No. Does monetary policy change, and are they going to even talk about it? Does fiscal policy change? No. We elect the conservative Republicans, and they make the deficit worse than the rest. Yeah, the American people are tired of that. They want real change. And to me, that means the only significant change we ought to have is get enough people in Washington that read the Constitution, obey the Constitution, do only the things that we're allowed to."
Paul also talked about the Federal reserve and the printing of money, saying that the candidate he likes the most on foreign policy (besides himself) is not a Republican at all, but liberal Ohio Congressman Dennis Kucinich.
It's good that you have allies on both sides of the aisle," Paul said, though he didn't say anything about having friends in the middle.