Republican presidential candidate George W. Bush is on the attack following Senator John McCain's upset victory in New Hampshire. In a new ad, Bush complains that "John McCain's ad about Governor Bush's tax plan isn't true....McCain's plan? A tax cut smaller than Clinton's...McCain echoes Washington Democrats."

The spot signals a tougher tack from the Texas Governor whose once-strong lead in polls has been dropping over the last week. Not only is Bush complaining that McCain does not share Republican values, but Governor Bush is trying to paint McCain as a Washington insider who is not to be trusted.

For his part, McCain is running an ad complaining about "George Bush's new negative ad attacking John McCain and distorting his position. Do we really want another politician in the White House America can't trust?" With McCain skipping the Delaware primary, the next big test is South Carolina on February 19.