WASHINGTON -- Sen. Al Franken has worked hard to eschew his comedic roots to prove to Minnesotans he is a serious senator.

After handily winning a re-election effort last year, the second-term Democrat is dipping his toe back in.

Franken is scheduled to appear on the Late Show With David Letterman Wednesday for the first time since 2008 -- before he was elected to a first term.

Before then, Franken was a regular on Letterman, first appearing in 1982 with his then-writing partner Tom Davis. He was a guest some 20 times in the 1980s and 1990s, when he was a writer for Saturday Night Live, staffers said Friday.

Apparently, there is no planned agenda, the two old friends will just likely riff.

Letterman's last show for CBS is scheduled for May 20.