Barack Obama, in his first appearance on "FOX News Sunday," says there will be no more debates before the two May 6 primaries despite repeated challenges from Hillary Clinton to meet him face-to-face.

Clinton challenged him again Saturday in Indiana, saying the two should meet for a one-on-one debate without moderators, Lincoln-Douglas-style.

That seems unlikely, given Obama's response when posed the debate question by FOX News' Chris Wallace.

The Illinois senator and Democratic front-runner spoke with Wallace Saturday in Marion, Ind., in an interview aired Sunday, ending a 772-day silent treatment toward the talk show.

The interview touched on topics ranging from his struggles attracting working-class voters to his criticism of John McCain to the Rev. Jeremiah Wright Jr., Obama's controversial former pastor.

Asked why he repeatedly was "ducking" Clinton's debate challenges before the Indiana and North Carolina primaries, Obama said, as he has before, that he just wants to spend time with voters.

"I'm not ducking. We've had 21 (debates), and so what we've said is, with two weeks, two big states, we want to make sure we're talking to as many folks possible on the ground taking questions from voters," he said, so no debates.

"We're not going to have debates between now and Indiana," he said.

Obama took a rapid-fire set of tough questions on his personal gaffes and controversies at the last ABC debate in Philadelphia before the Pennsylvania primary, which he lost.

Speaking in South Bend, Ind., Clinton taunted him a little, then proposed a compromise.

"You know, after the last debate in Philadelphia, Senator Obama's supporters complained a little bit about the tough questions. And you know, tough questions in the debate are nothing compared to the tough questions you get asked when you're president and you have to answer them to make tough decisions," she said.

"So here's my proposal: I'm offering Senator Obama the chance to debate me one-on-one, no moderators. Just the two of us, going for 90 minutes, asking and answering questions. We'll set whatever rules seem fair."

She formalized the request in a letter to the campaign. But Obama strategist David Axelrod said: "I think if Lincoln-Douglas had debated 21 times, I don't think there would be much appetite for another Lincoln-Douglas debate."

Wallace said that if Obama had won Pennsylvania he may not have accepted the FOX News Sunday invitation. But he said that once Obama met him for the interview, the Illinois senator was "friendly" and discussed several moderate-to-Republican viewpoints, making an apparent effort to broaden his appeal.

"He made it very clear he was not some left ... liberal and he had been mischaracterized as such," Wallace said. "I think this was an effort to sort of restore or regain the brand that he had some months ago, when he was saying there wasn't a Republican solution, or a Democratic solution. It was a new politics and it needed to be a coalition."

The interview is appearing on local FOX affiliate stations Sunday morning. "FOX News Sunday" airs on FOX News Channel at 2 p.m. and 6 p.m. EDT Sunday.

FOX News' Aaron Bruns and Bonney Kapp contributed to this report.