Gail Shister
TVNewser Columnist

Wanna host "Saturday Night Live?"

That's not funny.

When SNL asked Brian Williams to guest host this Saturday, he thought it was a joke.

"I wasn't sure they were serious," says the NBC anchor, who did a cameo last season on "Weekend Update." "These are funny people. When they said, 'We'd like you to host the show,' I said, 'Really?'

Once Williams understood it was on the real, he polled his "focus group," which includes his wife, Jane Stoddard Williams, their two kids, Tom Brokaw, Steve Capus, Jeff Zucker and assorted pals. "Not a single soul" turned thumbs down, he says.

Most SNL hosts spend the week in rehearsals. How will Williams swing it, given that he's co-moderator of the Democratic presidential debate Tuesday night in Philadelphia?

"They're going to have to work around it," he says. "Any SNL duties come at the end of my Nightly News work day." He plans to rehearse at about 7 p.m. Wednesday through Friday

Williams turned down SNL's host offer last year because he didn't consider it seemly for someone in his position. He did a 180 "after rolling it around in my head for a year."

No rolling necessary, BW. Most evening news viewers are asleep by 11:30 (10:30ct).

"I'm looking to have a little fun on my night off. Normally, I'm as serious a guy as you'll ever meet during work hours. There's more than one dimension to life."

Tim Russert, Williams' co-moderator for the Dem debate, labels his SNL stint as "an honor for this news division.

"It's a form of recognition that he's a complete person. Brian's a tremendous anchor who also, God forbid, has a sense of humor."