By Krissah Thompson

This post has been updated.

YORK, Pa. --Vice President Biden kicked off a Labor Day weekend full of campaign rallies by criticizing Mitt Romney's GOP acceptance speech.

The vice president's toughest words were for Romney's foreign policy agenda. "He said it was a mistake to end the war in Iraq and bring all of our warriors home," Biden said, as the Sunday afternoon crowd gathered at West York Area High School booed. "He said it was a mistake to set an end date for our warriors in Afghanistan and bring them home. He implies by the speech that he's ready to go to war in Syria and Iran."

The rowdy Obama supporters packed into the hot school gymnasium also booed as Biden lit into GOP vice presidential candidate Paul Ryan, criticizing the Wisconsin congressman for implying in his acceptance speech that the GM plant in Janesville, Wis. closed during Obama's time in office.

"Folks, I don't need you booing. I need you voting," Biden said at one point throwing up his hands, while using a version of the line that has become a staple for President Obama on the campaign trail.

Ryan "was right about one thing," Biden continued. "The closing of that plant devastated his community and was devastating to those people who lost their jobs. What he didn't tell you was that plant in Janesville actually closed while President Bush was still president of the United states of America!"

"GM is alive!" a woman in the audience shouted.

Romney campaign spokeswoman Amanda Henneberg hit back at Biden's  dismissal of the former governor's foreign policy agenda. "It's no wonder that a politician who has been wrong about every major foreign policy question of the last 30 years is wrong on every count about Gov. Romney's strategy to restore America's leadership role in the world," she said in an e-mail. "President Obama has undermined the pillars of American strength abroad with his failure to get our economy going, his devastating defense cuts, and his shameful failure to defend our values."