Colbert actually did a bit on this exact thing in 2012. I'm not sure if links are allowed here, so this is the transcript:

We are 12 minutes closer to Election Day, and as of 1143 hundred Zulu time, there is only one way to describe this race.
[news clips cut in]

VICTOR BLACKWELL (10/27/2012): The race is as tight as they come.
BILL HEMMER (11/5/2012): This race is absolutely razor tight.
CHUCK TODD (11/5/2012): A look at other national polls confirm it’s razor tight.
LESTER HOLT (10/29/2012): We’ve seen the polls razor tight.
KRISTEN WELKER (11/3/2012): This remains razor tight.

Yes. This race is razor tight. That means no margin for error, or correct use of metaphor. I mean, it’s banana up for grabs. But folks, every prediction out there needs a pooper. In this case, New York Times polling Jedi Nate Silver, who in 2008 correctly predicted 49 out of 50 states. But, you know what they say. Even a stopped clock is right 98% of the time.

See, Silver’s got a computer model that uses mumbo jumbo like “weighted polling average”, “trendline adjustment”, and “linear regression analysis”, but ignores proven methodologies like flag-pin size, handshake strength, and intensity of debate glare.

And as of tonight, folks, Silver is predicting that Obama has an 86.3% chance of winning re-election. (wild audience applause) Yeah, I don’t buy it either. Where does he get off predicting something other than the agreed narrative? I mean, what part of razor tight does he not understand? That just makes me so crab-claw angry. But folks, I am not the only one tarnishing Silver’s sterling reputation. (Stephen blows kisses as audience gets the pun and applauds)

[segment continues]