Carl Kasell, sober-voiced radio newsman-turned-comic foil, is retiring from his role as official judge and scorekeeper of the hit National Public Radio comedy-quiz show "Wait Wait … Don't Tell Me!"

Kasell, a former NPR "Morning Edition" newsreader who turns 80 in April, told the Two-Way, NPR's in-house blog, that the Chicago-based show made him "the luckiest man around to be able to have worked at a job I love for so many years."

Kasell will continue to make occasional appearances as the show's Scorekeeper Emeritus. He was not doing further interviews, an NPR spokesman said.

The retirement as regular weekly show personality will come "this spring" after proper farewell shows, in Chicago or Kasell's home of Washington, D.C., or both, show host Peter Sagal said.

"We want him to be celebrated every place we go for the next few months," Sagal said. "Carl is the popular person on our show. He is the heart and star of it.

"He is probably the single most beloved person on NPR. He was everybody's favorite grandfather, uncle or, going back some, brother by another name."

Kasell was ill and off the show for about six weeks last May and June, and the show's regular tapings at Chicago's Chase Bank Auditorium and in other cities have required him to fly to the destinations nearly every week.

The retirement will give Sagal and his producers a chance to re-examine the role of announcer and scorekeeper, in part "because it would be stupid to try to replace Carl," Sagal said. "There's been this huge part of the show built on the immense gravitas of this guy, and we've gotten huge mileage out of making this guy do funny things."

The show's scripts frequently have Kasell making odd sounds or doing not particularly persuasive imitations of newsmakers.

For three decades, ending in 2009, he was the news anchor on NPR's signature "Morning Edition" news program, but he told the radio service's blog that "my favorite time at NPR has been 'Wait Wait … Don't Tell Me!' "

With the quiz show since its inception in 1998, Kasell reads the fill-in-the-blank limericks for the show's Listener Limerick Challenge, and the regular Who's Carl This Time? game has had him reading quotations by newsmakers.

His voice recording a voice-mail or answering-machine greeting has long been the show's standard prize for people who win the various in-show contests. He will continue in that role.

Hiring Kasell was a key strategic decision for the show, a sign that it was OK to laugh, in this context, along with NPR, said Torey Malatia, who ran Chicago Public Media from 1996 until last July.

"Having Carl, one of public radio journalism's most thoughtful, professional and cultured voices, be off-the-wall funny [was] a wink equal to the annual White House Correspondents Association dinner," Malatia said.

The show's makers will think about how best to fill Kasell's on-air job as various people fill in after Kasell's retirement, Sagal said.

Asked if another straight-laced newsman, veteran Chicago TV anchor Bill Kurtis, might take the role, Sagal suggested that the show could be looking for generational and stylistic change, as well.

"Bill Kurtis is great, and he's another retired gentleman in his 70s," Sagal said. "As you know, Bill Kurtis has filled in for us very well. I would not be surprised if he came back and helped us out in the short term."

But so significant a personnel change gives the staff an opportunity to tinker with the format in a way hit NPR shows rarely are able to do, for fear of offending viewers.

"For example," Sagal said, "what if we got somebody who was really good at sound effects? What if we got somebody who was a stand-up comedian? A really good mimic? There's all kinds of things we could do. Even a beatboxer."

The show, which uses Sagal, Kasell and a rotating panel of three comics to poke fun at the news, is produced by Chicago Public Media and NPR. It tallies 3.8 million listeners and 2 million podcast downloads weekly, according to NPR.