Mitt Romney 'should come clean' on his taxes, says Obama camp in new ad

The presidential candidates are criticizing each other in new television commercials aimed at winning working-class voters who could help swing the election, pitting Republican Mitt Romney's wealth against the loss of American jobs to China on President Barack Obama's watch.

As Romney dispatched running mate Paul Ryan to kick off a three-day bus tour in the critical battleground of Ohio, Obama began running an ad in the state trying to use his GOP rival's own words against him.

It's the campaign's first spot using Romney's comments that 47 percent of voters pay no income tax, and believe they are victims and entitled to government assistance. The 30-second ad also points out that Romney paid just 14.1 percent in federal taxes last year on $13.7 million in income and refuses to release his returns before 2010.

"Maybe instead of attacking others on taxes, he should come clean on his," the ad says.

Romney is trying to shift the debate off his personal wealth and private comments to donors to worker resentment over jobs moving to China. His new ad released Monday is his latest salvo in a string of criticism against Obama's handling of the rising Asian power.

The commercial showed a photo of a shuttered factory and says fewer Americans are working as China steals the country's ideas and technology. "Obama had years to stand up to China. We can't afford four more," the spot concludes.

Six weeks out from the election, Obama holds a slim lead over Romney in most battleground states. The Republican is seeking to right his campaign following a rough stretch that included the release of his secretly recorded remarks about the 47 percent and criticism that he's not campaigning hard enough for the White House.

Romney acknowledged Sunday that he was trailing the president in several key states. But he promised to spend less time courting donors and more time with voters.

"I know that in the coming six weeks they're very unlikely to stay where they are today," Romney said of the polls.

The Republican was scheduled to campaign Monday in Colorado, where aides added a rally in an attempt to deflect the criticism from within his own party. Romney was to join Ryan in Ohio on Tuesday for the final two days of bus tour.

Obama will spend Monday and Tuesday tending to official duties at the United Nations. But his condensed schedule at the annual gathering of world leaders underscored that his focus is largely on the campaign.

Voters in more than two dozen states are already casting ballots in early voting for the presidential election, meaning everything the candidates do now could influence votes already being cast.