So Letterman is retiring. Now, CBS has a top choice and that's none other than Stephen Colbert. He has indicated that he is willing to take over the Late Show when the time comes.

Colbert has not had any formal contract discussions with CBS yet, but sources say that he first engaged with network executives while Letterman was still mulling the time of retirement. Other candidates include Jon Stewart.

Colbert's contract to host The Colbert Report on Comedy Central runs through the end of 2014, which would free him up in time to move over to CBS when Letterman ends his 33-year run in late-night TV.

“We don’t have the timing of this precisely down; it will be at least a year or so," Letterman said on Thursday's episode of the Late Show. "But at some time in the not-too-distant future — 2015, for the love of God."