Vice President Joe Biden said Sunday that Republican rival Mitt Romney is ‘‘ready to go to war in Syria and Iran’’ while hurting the middle class.

The warning came during a campaign stop in York, PA., designed to promote President Barack Obama’s economic policies among white, working-class voters.

The thrust of Biden’s pitch has been that America is digging out from the 2008 economic collapse and that Romney would take the country backward. But Biden, a foreign policy heavyweight, also cautioned voters that Romney would adopt policies that favor confrontation over cooperation.

‘‘He said it was a mistake to end the war in Iraq and bring all of our warriors home,’’ Biden said of Romney. ‘‘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.’’

Biden made the claim about Syria and Iran without offering specifics; his campaign did not immediately respond to a request for details.

Romney’s campaign dismissed the criticism. ‘‘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,’’ spokeswoman Amanda Hennenberg said.

Romney has said he would consider military action in Syria if the war-torn country’s chemical weapons were at risk of falling into the wrong hands. Obama, who has opposed military action in Syria, has made similar remarks, calling it a ‘‘red line’’ for the U.S. if Syrian President Bashar Assad’s regime were to use chemical or biological weapons.

And like Obama, Romney has said the U.S. must keep all options on the table, including a military strike, when dealing with Iran. But Romney has suggested that Obama has been too soft on Iran and — without offering specifics himself — said he would prevent Iran from obtaining a nuclear weapon.

But Biden’s remarks, in an audience of about 1,400 in a high school gymnasium, focused mostly on the economy.

‘‘This is no time to turn back. We have to continue to move forward,’’ he said. ‘‘Folks, I am absolutely certain — there’s not a single doubt in my mind — that we are on the way to rebuilding this country stronger than it was before.’’

Biden said Romney’s policies favor the rich at the expense of the middle class.

‘‘On top of maintaining that tax cut ... they want to add another $250,000-a-year tax cut for everyone making over a million dollars,’’ Biden said. ‘‘So you wonder why they’re eviscerating the middle class, and this has a giant price tag.’’

‘‘These are the very policies that put America’s greatness in jeopardy in the first place,’’ he added.

He also noted Ryan had not told the complete story when he talked about a General Motors plant that closed in Janesville, Wis., his hometown.

‘‘What he didn’t tell you was that plant in Janesville actually closed while President Bush was still president,’’ Biden said before flying to Wisconsin later in the day.