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