The issue is their treatment in debates. Obama is objecting to the questions posed this week in one moderated by ABC News. Many of the toughest questions were targeted at Obama, the front-runner for the nomination, and he's said too much time was spent on political divisions instead of issues that matter to Americans.
Clinton said Friday that if Obama thinks the debate was tough, it pales in comparison to the pressures a president faces.
"I'm with Harry Truman on this - if you can't stand the heat get out of the kitchen," she told voters while campaigning in Pennsylvania. "Just speaking for myself, I am very comfortable in the kitchen."
But it wasn't so long ago that Clinton was the front-runner and complaining about her treatment in debates. After a debate last fall, her campaign compiled clips of her being targeted, and called it the "Politics of Pile On." In late February, Clinton complained that she always got asked the first question.
"Her blatant hypocrisy here is stunning," responded Obama spokesman Bill Burton.
The most recent debate Wednesday night was the most watched of this election cycle and has generated some negative reviews for ABC. Obama supporters have made some of the loudest objections, and the Obama campaign sent out a fundraising appeal off the debate titled "Gotcha."
Obama said Thursday that the moderators "like stirring up controversy and they like playing"
"Senator Clinton looked in her element," Obama added. "She was taking every opportunity to get a dig in there. That's her right to kind of twist the knife a little bit ... that's the lesson she learned when Republicans did it to her in the 1990s."
Clinton said Friday that getting tough questions is part of what happens in a debate and campaign. "Having been in the White House for eight years and seeing what happens in terms of the pressures and the stresses on a president, that was nothing," she said.
"We were both asked some pretty tough questions and that's part of what happens in a debate and in a campaign, and I know he spent all day yesterday complaining about the hard questions he was asked," Clinton also said in an interview with Philadelphia television station FOX 29, although Obama did not complain about the difficulty of the questions, just the substance.
"Being asked tough questions in a debate is nothing like the pressures you face inside the White House," she said, according to a transcript of her interview provided by her campaign.
Former President Bill Clinton also weighed in on the controversy, saying that "they have been beating up on us for 15 months."
"I didn't hear her whining when he said she was untruthful in Iowa or called her the senator from Punjab," Mr. Clinton said in St. Mary's, Pa. on Thursday. "And you know they said some pretty rough things about me too. But you know this is contact sport if you don't want to play keep your uniform off. But the truth is… this has been basically a positive campaign on the issues and on the records and on the experience. "
Both Clinton and Obama were campaigning in Pennsylvania Friday, which holds its primary Tuesday - their first contest in seven weeks. Obama leads Clinton in overall delegates, 1,638-1,496, but neither is close to achieving the 2,025 needed to win the nomination.
One of Clinton's supporters, New Jersey Gov. Jon Corzine, said Friday that Clinton needs a big win in Pennsylvania if she hopes to overtake Obama. A loss in the Keystone state would be "pretty much a door closer," Corzine said.
Another Clinton supporter encouraged her to challenge Obama all the way to the convention.
"I think I also speak for more than 1,500 delegates who want you to go to the convention and to fight for your right to represent our country as president of the United States," Luis Cortez said as he introduced Clinton to speak at Esperanza High School, the Philadelphia charter academy that he heads.