If the intent was to sharpen the contrast between the two presidential campaigns and motivate part of the conservative base at a time when new polls show Mr. Obama gaining a slight advantage, Mr. Ryan may have succeeded. He was frequently cheered.

In response, the Obama campaign criticized Mr. Ryan’s tone as much as his substance. “Today, speaking at a values summit, he unleashed a series of over-the-top, dishonest attacks against the president that once again reminded voters that he’s just not ready for prime time,” said Danny Kanner, an Obama campaign spokesman. “In the not too distant past, Mitt Romney and Congressman Ryan said they wanted a serious debate on substantive issues. We’re still waiting.”

The Romneys were unusually playful in their joint interview, part of an effort to humanize Mr. Romney that began at the Republican National Convention and included an intimate portrait of the couple at their New Hampshire lake house filmed for CBS News’s “60 Minutes.”

When Mr. Strahan asked Mr. Romney what he wears to bed, the former governor of Massachusetts asked: “Really? Really?” before saying: “I hear the best answer is as little as possible.”

Asked for an embarrassing story, Mrs. Romney delighted the audience with a tale about the time she and Anita Perry, the wife of Gov. Rick Perry of Texas, were wandering around the White House and stumbled on President George W. Bush getting a massage.

“He was covered up, but I was so embarrassed that the next time I did see him I didn’t know what I was going to say to him,” she recalled. “We were going down the elevator from the White House, going to an event together, and I walked up to the elevator and am just like blushing, blushing, blushing, and he looks at me and he winks as he does and says, ‘I look pretty good, don’t I?’ ”