"She knows better. Shame on her. Shame on her," Obama told an audience at a union hall here.

The Illinois senator has spent two days on the defensive after comments he made at a San Francisco fundraiser suggesting working class people are bitter about their economic circumstances and "cling to guns and religion" as a result. Clinton has pounded him for the remarks, calling him "elitist and divisive."

After reiterating his regret for his choice of words, Obama turned the tables on Clinton _ noting that she accepted campaign contributions from drug and insurance company lobbyists and mocking, among other things, her sudden fealty to the rights of gun owners.

"She is running around talking about how this is an insult to sportsmen, how she values the Second Amendment. She's talking like she's Annie Oakley," Obama said, invoking the famed female sharpshooter immortalized in the musical "Anne Get Your Gun."

Obama continued, saying "Hillary Clinton is out there like she's on the duck blind every Sunday. She's packing a six-shooter. Come on, she knows better. That's some politics being played by Hillary Clinton."

Obama said the former first lady's history in the White House and Senate proved she was not as sensitive to the concerns of working class voters in Pennsylvania and elsewhere as she tried to suggest. Pennsylvania's primary is April 22.

"I just have to remind people of the track record," Obama said. "This is the same person who took money from financial folks on Wall Street and then voted for bankruptcy bill that makes it harder for folks right here in Pennsylvania to get a fair shake. Who do you think is out of touch?

"This is the same person who spent a decade with her husband campaigning for NAFTA, and now goes around saying she's opposed to NAFTA," Obama said, referring to the North American Free Trade Agreement that is widely unpopular in blue collar communities.

The Clinton campaign issued a quick retort to Obama's comments.

"For months, Barack Obama and his campaign have relentlessly attacked Hillary Clinton's character and integrity by using Republican talking points from the 1990s," said spokesman Phil Singer. "The shame is his. Senator Clinton does know better _ she knows better than to condescend and talk down to voters like Senator Obama did."