A Democratic super PAC is airing a new ad attacking Republican George Allen’s first six years in the U.S. Senate.

The ad buy comes just days after Crossroads GPS, a group headed by Republican strategist Karl Rove, began airing its own ad blasting Allen’s November opponent, Democrat Tim Kaine. The dueling ad buys are an example of the kind of tit-for-tat sparring expected throughout the fall as outside groups spend millions to influence one of the most anticipated Senate matchups of the election.

The new Democratic ad from Majority PAC hits Allen for supporting major spending initiatives during his first term in the Senate, but it also offers a positive message about Kaine.

“Our new ad in Virginia contrasts the budget disaster that George Allen created in Washington with the booming Virginia economy under Governor Tim Kaine,” said Majority PAC strategist J.B. Poersch. “While Crossroads may want to pretend otherwise, George Allen has already had his chance in the Senate, and he used it to turn a record surplus into an enormous deficit.”

The ad is running in urban markets across the state, including Northern Virginia. Majority PAC did not reveal how much it's spending to air the new ad., but it's part of a six-state counter-attack against a recent $4.6 million ad purchase by Crossroads.

"No attempt to rewrite Tim Kaine’s record will erase the fact that as Governor he tried to raise taxes by billions, made 'significant' cuts to higher education that drove up tuition costs by over 30 percent, and watched as Virginia’s unemployment rate more than doubled with 100,000 Virginians losing their job," Allen spokeswoman Emily Davis said. "Virginians are looking for a proven leader like George Allen who will fight to rein in an over-spending government with a Balanced Budget Amendment, line item veto authority, and a paycheck penalty against Members of Congress who fail to pass a budget on time."