WASHINGTON, Pennsylvania (Reuters) - Presidential hopeful Barack Obama, accused of being elitist for remarks he made about small-town American voters, said on Tuesday the slap at his background is amusing and signals a nation in the midst of “political silly season.”

The Democratic senator, campaigning in Pennsylvania, dismissed the charges of being elitist and out of touch by fellow Democrat Hillary Clinton and by Republican John McCain as unfounded, given his background.

“I am amused about this notion of elitist, given that when you’re raised by a single mom, when you were on food stamps for a while when you were growing up, you went to school on scholarship,” he told a town hall meeting of U.S. military veterans in western Pennsylvania.

Obama has come under fire by opponents after he told an audience in San Francisco last week that economic problems led voters in some small towns to become “bitter” and “cling to guns or religion” as an outlet for their frustrations.

Neither of his wife Michelle’s parents attended college, and both he and his wife financed their educations with student loans, Obama said.

“We lived for the first 13 years of our marriage up until three years ago in a three-bedroom condo without a garage so if you live in Chicago that means you’re scraping ice every morning,” he said in rejecting the elitist label.

“When somebody makes that argument, particularly given that I’ve spent my entire life working with workers in low-income communities to try to make people’s lives a little bit better, that’s when you know you’re in political silly season,” said Obama, who leads Clinton in the tight race for the Democratic presidential nomination.

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“This is what we do politically when we start getting behind in races, and we start going on the attack,” he said.

The winner of the Democratic presidential nomination faces McCain, the Republican presumptive nominee, in the November general election.

Obama and his wife lived in a condominium they bought in 1993 for $277,500, The Boston Globe reported. They now live in a house for which they paid $1.95 million in 2005.

Clinton has condemned Obama’s remarks from last week in a political ad featuring a woman saying she was “insulted,” while McCain said the comments represented “a certain out-of-touch elitism.”

Obama’s comments on Tuesday came in response to a man in the audience who said he felt the label of elitist was not far from the label of “uppity,” a racially insulting term used against blacks.

Obama said he did not think there were racial overtones to the criticism.

(Editing by David Alexander and David Wiessler)