The remark was contained in an audiotape posted online at The Huffington Post, The Washington Post (NYSE:WPO) said Friday. On the tape, which was made at a San Francisco fundraiser, Obama said Pennsylvanians' frustrations come in part from failed domestic policies.

"You go into some of these small towns in Pennsylvania, and like a lot of small towns in the Midwest, the jobs have been gone now for 25 years and nothing's replaced them," he said.

Obama said both the Clinton and Bush administrations have let voters down.

"And 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 frustration."

An adviser to presumptive Republican nominee John McCain Said Obama's comment revealed "an elitism and condescension towards hardworking Americans that is nothing short of breathtaking."

Obama rival Hillary Clinton told a Pennsylvania audience Friday people in the state are "resilient" and "optimistic."

"Pennsylvanians don't need a president who looks down on them," she said. "They need a president who stands up for them, who fights for them."

Speaking Friday at a rally in Terre Haute, Ind., Obama said when he talks to voters, "there is frustration, and there is anger, and there is bitterness," CNN reported.

Obama said Pennsylvanians "are frustrated and for good reason, because for the last 25 years they've seen jobs shipped overseas, they've seen their economies collapse. They have lost their jobs, they've lost their pensions. They've lost their healthcare."