ORLANDO, Fla. –As Mitt Romney took a break from campaigning here Saturday to prepare for the next presidential debate, President Barack Obama’s campaign, seeking to slow the momentum his challenger gained from his widely praised performance in the first debate, released a new television ad accusing Romney of lying about taxes during Wednesday night’s clash.

The Obama ad, titled “Dishonest,” says Romney displayed “shocking dishonesty” when he denied from the debate stage that he favors $5 trillion in tax cuts that would benefit the wealthy. Set to dark music, the 33-second spot, which will air in eight battleground states, shows Romney’s statement and concludes: “This was dishonest.”

The campaigns have been battling over taxes ever since Romney, during one of the debate’s first exchanges, directly challenged Obama’s assertion that Romney’s tax plan would finance big breaks for the wealthy by wiping out popular deductions for those who earn less than $250,000 a year.

“I know that you and your running mate keep saying that. I know it’s a popular thing to say with a lot of people, but it’s not the case,” Romney said on stage in Denver. “I will not reduce the taxes paid by high-income Americans. And . . . I will not, under any circumstances, raise taxes on middle-income families.”

The statement marked an attempt by Romney to regain his footing on a crucial issue that is at the heart of his agenda for spurring economic growth and creating jobs. The president has held a consistent advantage in public opinion polls on the question of which candidate is more trusted on taxes.

Romney’s plan calls for cutting income-tax rates by 20 percent for people at all income levels, repealing the estate tax and the alternative minimum tax and wiping out capital gains taxes for middle-class families. Budget analysts say the cuts would reduce tax revenue by nearly $5 trillion during the next decade. Obama has attacked the plan for the past two months, citing a study by the nonpartisan Tax Policy Center that said to avoid increasing deficits, Romney would have to generate an equal sum by cutting various tax breaks that benefit the middle class.

The Romney campaign reacted sharply to the ad, with spokeswoman Amanda Henneberg saying in a statement that “independent fact checkers – and even his own campaign – have admitted that President Obama is spreading falsehoods about Mitt Romney’s tax plan. It’s clear the President is willing to say and do anything to avoid talking about his own record of fewer jobs, declining incomes and record poverty.”

Romney’s campaign has said that it is Obama who has a secret plan to raise taxes on the middle class, an assertion that the new Obama ad also derided as false.

Republicans and even many Democrats concluded that Romney easily won Wednesday’s debate, and Obama has since been battling to recover his lost momentum. Those efforts were aided by Friday’s 0.3 percent dip in the U.S. unemployment rate, and the president’s campaign said Saturday that it was close to raising $1 billion after posting its strongest fundraising month of the year in September, with $181 million.

Romney was spending a quiet day off the campaign trail Saturday, engaged in preparations for the next debate, scheduled for Oct. 16 in New York, aides said. The former Massachusetts governor was scheduled to attend a “victory rally” Saturday evening in Apopka, Fla.

Romney’s wife, Ann, made a surprise visit to a Romney campaign office in Orlando on Saturday, a day on which the campaign is asking volunteers to call voters nationwide. She carried two pizzas from Papa John’s for the volunteers and made calls to two Orlando voters.

Newsletter