The 463 days is of course a metaphor as who the hell would be bothered to churn through Letterman's endlessly pro-Obama monologues.
For those more investigatively inclined the site
"Late Night Political Jokes"
does a day by day update on most of the late night talk shows monologues (what a terrible vocation) and they will search i vain for a negative comment from Letterman about Obama.
They will not be searching in vain for attacks on the various republican candidates-especially Gingrich. There will be endless mentions of Romney's dog episode from what, 30 years ago? But nothing about Obama's dog eating episode.
There is a sub-section at the site which includes "Obama Jokes" but again one will search for a long time before Letterman (D) has anything remotely bad to say about Obama.
Letterman is so blatantly in the tank for the Dem's the show should come with a DNC notice or the GOP should demand equal time.He was vicious against McCain in 2008 who did not fight back.
He came a cropper, as all bullies do, when he picked a fight with someone who fights back, i.e like a girl-Sarah Palin. He famously had to apologize to her on a number of occasions for attacking her daughter, and he has been circumspect when he rarely mentions her.
That is the key to handling the leftist media which includes the neurotics in show business-hit back hard and often and in the same coin otherwise they will trample all over you.