ANDERSON, Indiana (CNN) -- Sen. Hillary Clinton called for a Lincoln-Douglas-style debate with no moderator against her rival, Sen. Barack Obama, who says no more debates are needed before the May primaries.
In a TV interview to air Sunday, Obama flat-out denied any possibility that he would take part in a debate with Clinton before the next big round of primaries.
Shortly after maintaining that he isn't "ducking" debates with his Democratic rival, the Illinois senator admitted that the two hopefuls are "not going to have debates between now and Indiana."
Voters in Indiana and North Carolina will head to the polls May 6.
In the interview, Fox News' Chris Wallace asked Obama why he was ducking another one-on-one meeting.
"I'm not ducking one. We've had 21," Obama said. "We want to make sure we're talking to as many folks possible on the ground taking questions from voters." Watch more on the upcoming primaries »
In South Bend, Indiana, on Saturday, Clinton urged a debate modeled after the historic debates between Abraham Lincoln and Stephen Douglas in 1858.
They were a series of formal debates throughout Illinois in a campaign for one of two U.S. Senate seats.
"I'm offering Sen. Obama a 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 said.
"I think that it would give the people of Indiana and I assume a few Americans might tune in because nearly 11 million watched the Philadelphia debate. And I think they would love seeing that kind of debate and discussion. Remember, that's what happened during the Lincoln-Douglas debates," she added.
Clinton campaign manager Maggie Williams sent a letter to Obama campaign manager David Plouffe on Saturday asking for another debate.
"I have no doubt that Sen. Obama, who hails from that great state, understands how valuable and vital these national conversations were to the heart of America. ... If we debate, Americans will come," Williams wrote.
Williams, who replaced Patty Solis-Doyle when she stepped down from the campaign February 10, added that such a debate style would allow "no questions from the media. There would be equal time and equal opportunity to grapple with the important policy questions we are facing today."
Obama spokesman David Axelrod said Saturday that "we've debated a full work week of time already with Sen. Clinton, and we have 10 days, nine days left to meet voters in two important and large states."
"We want to use our time in that way. I don't think the public is clamoring for more debates."
Obama's refusal comes as a Newsweek magazine poll shows his popularity slipping nationwide.
According to the magazine, Obama's national lead over Clinton is down to 7 percentage points among Democratic voters and those leaning Democratic.
The magazine's poll last week showed his lead at 19 percent, higher than any other national poll.
Notable from the new numbers: Four in 10 registered voters have an unfavorable view of him now, including Republicans and independents.
Also, 41 percent say they have a less favorable view of him because of his connection to the Rev. Jeremiah Wright, whose controversial sermons made their way to the Internet.
Clinton, meanwhile, is looking to shore up her support from working-class voters with a stop Saturday in Indiana.
Talking about helping her father (a "small businessman," she emphasized) in his drapery business when she was growing up in Chicago, Clinton told the crowd, "It was one of the many experiences that really taught me the values that I've had my entire life. You know, hard work, self-reliance, individual responsibility. Good Midwestern values that we were raised with and that we believe in.
"I feel so fortunate to have that kind of background and upbringing, and I know that's what many of you have experienced as well here in Fort Wayne and across Indiana," she added.
Jabs at President Bush are always easy applause lines at Clinton's rallies, and she used his unpopularity to push her message Saturday.
"We need a president, especially after the last seven years of George Bush, who doesn't just make speeches about American values but understands them and lives them and believes them and wants to make sure that they are available for everybody."
When Obama made his now-famous "bitter" comments, Clinton was quick to cast him as an out-of-touch elitist. Now she is locked in a dead heat with Obama in Indiana polls with just over a week before the state's May 6 contest. Many consider it a must-win for the New York senator. E-mail to a friend
CNN political producers Alexander Marquardt, Ed Hornick and Chris Welch contributed to this report.