Comedians and late-night television hosts say they can skewer presumptive Republican presidential nominee Sen. John McCain, R-Ariz., about his age just as they did former U.s. President Bill Clinton's rumored infidelity, The New York Times reported Tuesday. But jokesters can't seem to find anything about Obama that can be turned into a laugh.

"We're carrion birds," Jon Stewart, host of Comedy Central's "The Daily Show," told the Times. "We're sitting up there saying 'Does he seem weak? Is he dehydrated yet? Let's attack.' "

Obama isn't "a comical figure," said Mike Barry, who started writing political jokes for Johnny Carson's monologues in the 1960s.

"A lot of people are excited about his candidacy," Mike Sweeney, Conan O'Brien's head writer, said to the newspaper. "It's almost like: 'Hey, don't go after this guy. He's a fresh face; cut him some slack.' "

Obama's race also is mentioned as a reason why he has been an elusive target for humor, the Times said.

"Anything that has even a whiff of being racist, no one is going to laugh," Rob Burnett, an executive producer for David Letterman, told the Times. "The audience is not going to allow anyone to do that."