For Obama, the grilling by host Tim Russert offered an opportunity to put the uproar surrounding his former pastor behind him. For Clinton, the town hall-style appearance hosted by her husband's one-time protegee George Stephanopoulos gave her the chance to burnish her populist message and persuade skeptical voters to like and trust her.
Coming off the toughest stretch in the primary campaign so far, Obama, the front-runner, had more to prove. After losing Pennsylvania's primary to Clinton on April 22, the Illinois senator has been forced to contend with explosive comments made by his longtime pastor, the Rev. Jeremiah Wright. At a press conference in Washington on Monday, Wright praised Nation of Islam leader Louis Farrakhan and reiterated his belief that that the U.S. government may have developed the AIDS virus to infect the black community and that it had invited the Sept. 11, 2001, attacks.
Obama denounced the remarks last week and was pressed further on that matter and other issues Sunday. Throughout it all, he was a virtual Zen master - displaying the calm self-confidence that has long made him seem both unflappable and aloof.
Russert noted that Obama already knew of some of his pastor's anti-American statements from widely viewed snippets of Wright's sermons on cable news and the Internet. Why did he break from Wright only after his appearance in Washington this week, Russert asked?
"I thought it was important for him to explain or at least to provide context for some of the things he said previously," Obama said, adding that Wright's press conference only made things worse.
"Not only did he amplify some of those comments and defend them vigorously, he added to it. He put gasoline on the fire," Obama said. "Not only was he interested in using this platform to make statements I fundamentally disagree with and offend me, he didn't have much regard for the moment we're in right now in the United States."
Obama said it was fair for voters to question his judgment in light of the Wright controversy, but he said he hoped they would do so in the context of his overall career. And he said he would remain a member at Chicago's Trinity United Church of Christ, where Wright recently stepped down as pastor.
"My commitment is to Christ, not to Reverend Wright," Obama said.
Obama showed a bit more passion when asked whether he would be vulnerable to a "Swift Boat"-style attack on his patriotism if he were to face Republican John McCain in the fall.
"I have never challenged other people's patriotism," he said. "I haven't challenge Hillary Clinton's or John McCain's and I will not stand by and allow somebody else to challenge mine."
He also got in a couple jabs at the former first lady, calling her proposed gas-tax holiday a "pander" and her vow to "obliterate" Iran if it attacked Israel nothing more than unhelpful bluster.
Clinton, for her part, turned in a feisty performance on "This Week" - at turns funny, combative and wonky. In contrast with Obama's coolheaded demeanor, Clinton was at times almost overeager - wide-eyed and smiling, rejecting an on-set armchair in favor of standing and gesturing to the audience.
Taking advantage of Obama's vulnerabilities among working-class voters, the New York senator has fashioned herself a champion of their concerns - in part by criticizing trade deals and sticking by her much-criticized proposal to lift the federal gas tax this summer.
"I think we've been for the last seven years seeing a tremendous amount of government power and elite opinion basically behind policies that haven't worked well for the middle class and hardworking Americans," Clinton said when pressed on why no prominent economists support the gas-tax holiday. "I'll tell you what, I'm not going to put my lot in with economists."
She stuck to her guns even as an audience member said she felt she was being "pandered to" by the gas-tax holiday plan.
Clinton insisted she had opposed NAFTA during her husband's presidency, although there is little evidence to suggest she worked against it at the time. She even conscripted Stephanopoulos into service to support her story.
"Now, you remember this, because George did work in that '92 campaign, and George and I actually were against NAFTA," Clinton said. "I'm talking about him in his previous life, before he was an objective journalist and didn't have opinions about such matters."
She also joked about Rush Limbaugh, saying the conservative radio host "always had a crush on me."
