California gubernatorial nominee Jerry Brown has become desperate in his campaign against Republican opponent Meg Whitman.

Video from a campaign event shows Brown attacking former President Bill Clinton, calling him a “liar” and rehashing his affair with Monica Lewinsky. Brown even mocks Clinton’s “I did not have sexual relations with that woman” statement, replacing “sexual relations” with taxes and “woman” with state. It’s pure blue-on-blue action.

So why is the Democratic gubernatorial nominee in a deep blue state attacking the only living popular former Democratic president? Here’s your answer. Meg Whitman has a new television ad showing Bill Clinton calling Brown a liar who raised taxes and left California with a deficit. The devastating footage comes from a 1992 debate for the Democratic nomination.

Clearly the Whitman ad has struck a nerve with the Brown campaign. In fact, Mark Halperin of Time calls it the best ad from any campaign in the 2010 election season. Judging by the Brown campaign’s desperate response, that would appear to be an accurate assessment.