Video from Countdown with Keith Olbermann in which Markos Moulitsas threatens a primary challenge for Rep. Dennis Kucinich (D., Ohio), who has vowed to vote against a health-care bill without a public option.

Moulitsas compares Kucinich to Ralph Nader, and accuses him of “undermining reform” buy “making common cause with Republicans,” which he calls a “perfect excuse. . . for a primary challenge.”