Mitt Romney barnstormed battleground Ohio and pledged "I'm not going to raise taxes on anyone" in a new commercial Wednesday as Republican running mate Paul Ryan and Vice President Joe Biden looked ahead to their only debate of the 2012 campaign.

President Barack Obama spent a rare campaign day at the White House, leaving it to aides to accuse Romney of dishonesty for saying he won't pursue any abortion-related legislation if he wins the White House. The former Massachusetts governor, who once supported abortion rights, reaffirmed his opposition.

Neither Biden nor Ryan had any public appearances the day before Thursday night's 90-minute debate in Danville, Ky.

Vice presidential encounters rarely make a significant difference in a White House campaign, although aides engage in the same sort of attempt to shape public expectations as when the men at the top of the ticket are ready to face off.

For Ryan's camp, that meant whispering that the 42-year-old Wisconsin congressman and House Budget Committee chairman was comfortable discussing spending issues and domestic policy, but might not be able to hold his own on foreign policy, a Biden strong suit.

The vice president's side let it be known that Ryan is smart and wonky, a man who knows the budget better than anyone _ but it's a version that omits mention of Biden's nearly four decades of experience in government and his role as Obama's point man in budget negotiations with Republicans on an elusive deficit-reduction deal.

Not even Romney or Obama seemed to pay much attention to the chatter. Instead, each expressed confidence in his own understudy.

Whatever the impact of the Biden-Ryan encounter, last week's presidential debate boosted Romney in the polls nationally and in battleground states, to the point that Obama was still struggling to explain a performance even his aides and supporters say was subpar.

"I think it's fair to say I was just too polite," he told radio host Tom Joyner in an interview late Tuesday. "... But, you know, the good news is, is that's just the first one," he said, criticizing Romney for having made numerous claims last week that are untrue.

Public opinion polls suggested the impact of last week's debate was to wipe out most, if not all, of the gains Obama made following both parties' national conventions and the emergence in late summer of a videotape in which Romney spoke dismissively of the 47 percent of Americans whom he said pay no income taxes, feel like victims and don't take personal responsibilities for their lives.

Eager to capitalize, Romney told a factory audience in Ohio during the day: "My whole passion is about helping the American people who are struggling right now ... The president says he's for the middle class. How have they done under his presidency? Not so well."

The Republican challenger's new television commercial was an appeal to voters' pocketbooks _ and also a rebuttal to Obama's claim that Romney had a plan to cut taxes by $5 trillion on the wealthy that would mean higher taxes for the middle class.

"The president would prefer raising taxes," Romney is shown saying in an exchange from last week's debate. "I'm not going to raise taxes on anyone ... My priority is putting people back to work in America."

Unemployment and the economy have been the dominant issues in the race for the presidency, and while Romney gained from the debate, last week's drop in the jobless rate to 7.8 percent gave Obama a new talking point for the Democratic claim that his policies are helping the country recover, however slowly, from the worst recession in decades.

Romney also sought to lay any abortion-related controversy to rest as he campaigned across Ohio, a battleground with 18 electoral votes and one of the places where he has gained ground since last week's debate.

"I think I've said time and again that I'm a pro-life candidate and I'll be a pro-life president," he said, renewing his promise to cut off federal aid for Planned Parenthood and implement a ban on the use of foreign aid for abortions overseas.

But by the time he spoke, Obama's aides had already jumped on comments from an interview with The Des Moines Register in which Romney said "there's no legislation with regards to abortion that I'm familiar with that would become part of my agenda."

Stephanie Cutter, Obama's deputy campaign manager, told reporters on a conference call that Romney was "cynically and dishonestly" hiding his positions on women's issues. "We're not saying he's changed his mind on these issues. We're saying he's trying to cover up his beliefs," she said.

For entirely different reasons, one prominent anti-abortion group agreed that he shouldn't.

As if to remind Romney of his previous statements on the issue, the head of the anti-abortion group Susan B. Anthony List distributed an article he wrote last summer vowing to prohibit federal funding for Planned Parenthood and to support legislation that would "protect unborn children who are capable of feeling pain from abortion."

"We have full confidence that as president, Gov. Romney will stand by the pro-life commitments," said Marjorie Dannenfelser, the group's president.

Romney's wife, Ann, took a turn as guest host on ABC's "Good Morning America" and spoke candidly about experiencing depression after she was diagnosed with multiple sclerosis 14 years ago. She said horses helped her recover her mental health.

"I was very, very weak and very much worried about my life, thinking I was going to be in a wheelchair as well. Turned to horses, my life has been dramatically different," she said. "They gave me the energy, the passion to get out of bed when I was so sick that I didn't think I'd ever want to get out of bed."

Mrs. Romney is part-owner of a horse that competed this summer in the Olympic sport of dressage, the equine equivalent of ballet.

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Espo reported from Washington. Associated Press writers Nedra Pickler, Julie Pace, Philip Elliott and Matthew Daly in Washington contributed to this report.