Play of the Day -- Mitt Romney's blue collar comedy tour

Colbert mocks Romney for factory story.

Mitt Romney this week tried get laughs by telling a story about his father -- shutting down a factory.

"It's like he's on the Blue Collar Comedy Tour -- if the comedy was about losing blue-collar jobs," Stephen Colbert joked.

Don't miss today's Must See Moment at 2:04 when David Letterman presents "Why They're Still Running."