"Democrats and Republicans are interesting because Republicans really laugh at themselves more. Like when Bush came on, it was, 'We want to do a skit, we're kind of making fun of… — 'Yeah, go ahead!'" said Leno on NBC's "Press Pass" with David Gregory, who appeared on Leno's show earlier in April.
Former Vice President Al Gore wasn't quite as easy going on camera as former President Bush, according to Leno.
"We went up to Al Gore, 'can we do this skit?' — 'Hang on.' And there was this focus group, and then media people came in: 'Where will Al be sitting? Will Al have the punchline?," Leno said.
The comedian told Gregory that politics has "got it all" when it comes to fodder for his comedic material.
"Politics is pretty good ... That’s about the best because it has everything real life has: a lot of sex, money, attractive people, unattractive people trying to be attractive people. Yeah, it’s got it all," he said.
Among the primary season's crop of GOP presidential hopefuls, Leno said Rick Santorum's candidacy provided "a lot of laughs." And Romney's awkward campaign trail moment, praising the height of the trees in Michigan, landed him on the show's "Kiss-ass Candidate of the Night" segment.
"It's very funny to watch rich people try pretend they're regular people. And there's nothing wrong with being a rich person," Leno said.
Despite jabs at the presumptive GOP nominee, Leno praised Romney's sense of humor.
"I like the fact that I can do weeks of Mitt Romney jokes, and Mitt Romney then comes here. Because I haven't insulted his religion … I mean I've made fun of him, but I haven't questioned his patriotism or his loyalty or his family," he said.
When asked whether President Obama is an easy target, Leno lamented the "golden age of comedy" — the Clinton and Bush years.
"The great thing about Clinton and Bush — like with Clinton: most people don't understand Afghanistan, have no idea what the nuclear armament, they don’t know. But they all know a guy like Bill," Leno said.
And if you're wondering whether he gets pushback from the subjects of his political humor, Leno said he hears from them often.
"And sometimes it’s justified," he said.