"If I worded things in a way that made people offended, I deeply regret that," Obama said in an interview with the Winston-Salem (N.C.) Journal.
But the Clinton campaign fueled the controversy in every place and every way it could, hoping charges that Obama is elitist and arrogant will resonate with the swing voters the candidates are vying for not only in Pennsylvania, but in upcoming primaries in Indiana and North Carolina as well.
Political insiders differed on whether Obama's comments, which came to light Friday, would become a full-blown political disaster that could prompt party leaders to try to steer the nomination to Clinton even though Obama has more pledged delegates. Clinton supporters were eagerly hoping so.
They handed out "I'm not bitter" stickers in North Carolina, and held a conference call of Pennsylvania mayors to denounce the Illinois senator. In Indiana, Clinton did the work herself, telling plant workers in Indianapolis that Obama's comments were "elitist and out of touch."
At issue are comments he made privately at a fundraiser in San Francisco last Sunday. He was trying to explain his troubles winning over some working-class voters, saying they have become frustrated with economic conditions:
"It's not surprising, then, they get bitter, they cling to guns or religion or antipathy to people who aren't like them or anti-immigrant sentiment or anti-trade sentiment as a way to explain their frustrations."
The comments, posted Friday on The Huffington Post Web site, set off a blast of criticism from Clinton, Republican nominee-in-waiting John McCain and other GOP officials, and drew attention to a potential Obama weakness - the image some have that the Harvard-trained lawyer is arrogant and aloof.
His campaign scrambled to defuse possible damage.
There has been a small "political flare-up because I said something that everybody knows is true, which is that there are a whole bunch of folks in small towns in Pennsylvania, in towns right here in Indiana, in my hometown in Illinois, who are bitter," Obama said Saturday morning at a town hall-style meeting at Ball State University in Muncie, Ind. "They are angry. They feel like they have been left behind. They feel like nobody is paying attention to what they're going through.
"So I said, well you know, when you're bitter you turn to what you can count on. So people, they vote about guns, or they take comfort from their faith and their family and their community. And they get mad about illegal immigrants who are coming over to this country."
After acknowledging his previous remarks in California could have been better phrased, he added:
"The truth is that these traditions that are passed on from generation to generation, those are important. That's what sustains us. But what is absolutely true is that people don't feel like they are being listened to."
Clinton attacked Obama's remarks much more harshly Saturday than she had the night before, calling them "demeaning." Her aides feel Obama has given them a big opening, pulling the spotlight away from troublesome stories such as former President Clinton's recent revisiting of his wife's misstatements about an airport landing in Bosnia 10 years ago.
Obama is trying to focus attention narrowly on his remarks, arguing there's no question that some working-class families are anxious and bitter. The Clinton campaign is parsing every word, focusing on what Obama said about religion, guns, immigration and trade.
Clinton hit all those themes in lengthy comments to manufacturing workers in Indianapolis.
"The people of faith I know don't 'cling' to religion because they're bitter. People embrace faith not because they are materially poor, but because they are spiritually rich," she said.
"I also disagree with Senator Obama's assertion that people in this country 'cling to guns' and have certain attitudes about immigration or trade simply out of frustration," Clinton added.
"People don't need a president who looks down on them," she said. "They need a president who stands up for them."
McCain's campaign piled on Obama, releasing a statement that also accused him of elitism.
One of Clinton's staunchest supporters, Sen. Evan Bayh, D-Ind., acknowledged there was some truth in Obama's remarks. But he said Republicans would use them against him anyway.
At a campaign rally in Wilson, N.C., former state Democratic Party chairman and current Clinton adviser Tom Hendrickson said rural voters don't need "liberal elites" telling them what to believe.
Bill Clinton was the featured speaker of the rally but avoided commenting on Obama's remarks. When asked about it afterward, he said simply, "I agree with what Hillary said."