President Barack Obama's campaign is running a new television ad claiming Republican Mitt Romney's policies would "hit the middle class harder."
The ad says Romney wants to extend tax cuts for millionaires at the expense of middle-income earners.
Romney has called for an extension of tax cuts first approved by George W. Bush for all income earners. Obama wants to let the cuts expire at the end of the year for families making more than $250,000 a year.
The ad says Romney doesn't see the "heavy load" the middle class is carrying.
The new spot is airing as Democrats open their party convention, where they'll focus on Obama's economic plans for the middle class.
The ad is running in Colorado, Iowa, New Hampshire, Nevada, Ohio and Virginia, key battleground states.