The furor could threaten Obama's chances in Pennsylvania, which votes on April 22, the next big showdown in his fight with Clinton for the Democratic nomination to face McCain in November's presidential election.
Clinton once enjoyed a big lead in Pennsylvania polls but that has dwindled to about 4 to 6 points in a state that has struggled from job losses and has a large number of the blue-collar voters who have been Clinton's biggest backers.
Both Democratic candidates have campaigned for the support of working-class families battling a shaky job market and a home foreclosure crisis.
Clinton visited a transmission assembly plant in Indianapolis that supplies U.S. tanks to talk about her plans to rejuvenate defense industries. She later took a tour and met with employees of a plant in Mishawaka, Indiana, that manufactures Humvees for the military.
Obama's comments "are not reflective of the values and beliefs of Americans," she said.
"Americans who believe in God believe it's a matter of personal faith. People embrace faith not because they are materially poor but because they are spiritually rich."
The Obama campaign accused Clinton of supporting special interests that leave common workers behind.
"We won't be lectured on being out of touch by Sen. Clinton, who believes lobbyists represent real people and is awash in their money," said Obama spokesman Hari Sevugan.
Obama also came under fire from McCain's campaign.
"Barack Obama's elitism allows him to believe that the American traditions that have contributed to the identity and greatness of this country are actually just frustrations and bitterness," McCain spokesman Tucker Bounds said.
Indiana Sen. Evan Bayh, a Clinton supporter, said the controversy could hurt Obama's effort to win over superdelegates, the Democratic Party insiders who are free to back any candidate at the August nominating convention and could decide the race.
Obama leads Clinton in pledged delegates won in state contests, but neither is likely to reach the 2,024 needed for nomination without support of the nearly 800 superdelegates.
"It's a real potential political problem and it's something for superdelegates and voters to think about," Bayh said.
"We have to win the election in November and the far right wing has a real good track record of using things like this against our candidates," he said.
