Al Franken: 'I make fun of the people who deserved it'

Sen. Al FrankenAlan (Al) Stuart FrankenReport: Conyers settled wrongful dismissal complaint over 'sexual advances' Arianna Huffington denies Franken behaved inappropriately in response to new photos Right way and wrong way MORE (D-Minn.) says he cracks jokes about political figures for a reason: They had it coming.

"I made fun of the people who deserved it, so Newt Gingrich, I made fun of Rush Limbaugh, and Bill O’Reilly at Fox," Franken told host Stephen Colber on Monday's "The Late Show."

Still, the former "Saturday Night Live" writer said there are several GOP senators who share his sense of humor, including former Sen. Jim DeMint (S.C.) and Sen. Lindsey GrahamLindsey Olin GrahamAlabama election has GOP racing against the clock Graham on Moore: 'We are about to give away a seat' key to Trump's agenda Tax plans show Congress putting donors over voters MORE (S.C.).

Franken recalled telling Graham that he would vote for him in last year's presidential primary if he were a Republican.

"Without hesitation he said, ‘That’s my problem,’ ” Franken said, calling Graham "very funny."

But the Minnesota lawmaker said some Republican lawmakers, like former Sen. Tom CoburnTom CoburnFormer GOP senator: Trump has a personality disorder Lobbying World -trillion debt puts US fiscal house on very shaky ground MORE (R-Okla.), haven't initially caught on to his punch lines.

“[Coburn] will admit that he doesn’t have a very good sense of humor so the first three or four interactions we had, we just kind of missed," Franken said.

He said the two men grabbed breakfast one day and Franken cracked a joke that Coburn, a former doctor, completely missed.

"To be a doctor in Oklahoma, do you have to have any formal education?" Franken recalled asking.

Coburn, according to Franken's account, passionately responded: "Yes, you got to go to medical school!"

But he said the meal improved after he "explained to him what jokes were, what the proper reaction to a joke is."

Franken's appearance on the late-night show is part of a string of appearances to promote his latest book, "Al Franken, Giant of the Senate."