Ryan also took a cultural jab at Obama's most famous gaffe from his 2008 campaign, when the then-Illinois senator spoke of "bitter" working-class people in small towns who resist change.
"You remember that one where he said people in places like Pennsylvania and Wisconsin, we cling to our guns and our religion?" Ryan said. "Hey. As a Catholic deer hunter: guilty as charged." He added, "That's what freedom is."
Ryan, who began the day at a steel plant outside Pittsburgh, was planting the Republican ticket's flag in Chester County, one of the Philadelphia suburban counties considered likely to decide which way the state and its 20 electoral votes will go Nov. 6.
Perhaps best-known for his budget proposal that would slash social spending and convert Medicare from a guaranteed federal health benefit to a plan that gives future retirees cash to buy their own health insurance, Ryan took pains to defend against Democrats' claims that he and GOP presidential nominee-to-be Mitt Romney would destroy the popular program - a potential political risk in Pennsylvania, where 15.6 percent of residents are over 65, according to the 2010 census.
About 38 percent of Pennsylvania seniors choose to get their Medicare benefits through a private insurer under the Medicare Advantage program, Ryan said, and the Affordable Care Act is cutting payments to those insurers by $716 billion as means of slowing the growth of Medicare expenses. Nearly half the state's seniors who use Medicare Advantage could lose their benefits, Ryan said, citing a Medicare actuarial study.
"What [Democrats] won't tell you is that they took Medicare and turned it into a piggy bank to pay for Obamacare," Ryan said. "The next time you hear from President Obama, tell him to keep his hands off Medicare."
Shortly before Ryan arrived, the back-and-forth over wealth, taxes, and electing the next president boiled over on the hot asphalt of a West Chester parking lot, where U.S. Sen. Frank Lautenberg of New Jersey, one of several Democrats staging a news conference to try to counter Ryan's event, clashed with a heckler.
"I'm one of the people who will get richer" if taxes are cut for the well-off, said Lautenberg, 88, a millionaire, "and I don't want that goddamn money. I want it to go to my country."
He glowered at the heckler, who was snapping pictures of him with a large camera and moments earlier had interrupted him, shouting, "Get the facts!"
"You get the facts, my friend," Lautenberg snapped back. He had, in effect, ventured behind political enemy lines - just outside the museum in an affluent pocket of Chester County, where thousands had flocked to see Ryan on the Wisconsin congressman's first campaign swing through Pennsylvania.
Soon, Republican partisans stuck in traffic for the event rolled down their windows to hurl epithets at the Democrats' group. "Communist!" one yelled. A feisty Lautenberg, the oldest member of the Senate, unleashed one of the harsher verbal assaults to date on the 42-year-old Ryan, chairman of the House Budget Committee.
"I call him Lyin' Ryan - and I don't spell it L-I-O-N," Lautenberg said at one point. "I'm telling him to leave Philadelphia and South Jersey and go back to the land of make-believe. People in this area rely on Medicare, and Paul Ryan has been trying to kill Medicare for years."
But the thousands who attended the West Chester rally were nothing but wild about Ryan, a hero to fiscal conservatives whom Romney announced as his running mate on Aug. 11.
"I love everything [Ryan] says. It resonates with me. He's great. I am a gal who loves a budget," said Victoria Smith, 52, of Paoli, a volunteer at the event. "We watch our family's budget like a hawk. It's great that finally somebody's watching over our country's budget."
Dave Hoffstad of West Goshen said Ryan "is right on target - with jobs, the economy." Hoffstad, who owns a building company, said, "I built my business, not Obama."
Later, Ryan attended a Union League reception in Philadelphia that was expected to raise up to $500,000 for the Victory program, a joint project of the Romney-Ryan campaign and the Republican National Committee.
As deep-pocketed donors strode up the Union League's curved exterior staircase, protesters from Occupy Philadelphia seethed behind police barricades across the street. About 50 demonstrators chanted, "Beat back the Romney attack." Earlier, several lay down in front of the steps to form what they called a "human red carpet."
Inside, Ryan was issuing a call to arms. "Why are we all here?" he told his Union League audience. "Because we realize this is not a normal election. This is a defining moment for our generation - we are going to determine what the trajectory of this nation is going to be."
He cast the election as a choice between moving toward what he called a European-style future in a second Obama term and an "opportunity society" with "upward mobility" that he promised a Romney administration would produce and safeguard.
"Are we going to throw in with a lot of other countries that were once great but are now in decline?" European economics equals the European debt crisis, he said. "Why would we want to emulate that?"
Contact Thomas Fitzgerald at 215-854-2718 or firstname.lastname@example.org, or follow on Twitter @tomfitzgerald.
Inquirer staff writer Jeremy Roebuck contributed to this article.