(CBS News) MINNEAPOLIS -- In his first public appearance since causing an uproar on the campaign trail last week, Vice President Joe Biden didn't mention the word "chains" -- but he also didn't let up on the tough talk during a Tuesday swing through Minnesota.
Biden enraged Republicans when he declared in Virginia before a racially mixed audience that Mitt Romney would them "back in chains" -- a comment the GOP said conjured up unfair racial divisions. But in Minneapolis, the vice president did deride Romney for "changing his tune" on the issue of China.
Biden said the administration had taken measures to stop Chinese-made tires from overwhelming the American market, establishing a trade enforcement unit.
"I was surprised by Romney's response to our actions when we did that," Biden said. "He called us - our actions against China -- protectionism. He said, quote, it was bad for the nation, bad that we exercised our rights under international trade agreements to stem the flow of cheap Chinese tires saving American jobs.
"Tell that to the people making those tires here in the United States of America. A bad thing to save jobs? I got news for you. The president and I brought trade cases against China twice the rate of any previous administration, and as long as they're not playing by the rules, we're going to continue to, no matter what Romney calls it."
Biden further assailed the former Massachusetts governor for now saying that the Obama administration had not been tough enough on China. Romney has stated that he would label the country a currency manipulator if elected.
"And now, what's fascinating, what's fascinating, like a lot of other things, I know this will shock you: Romney's changing his tune," Biden said. "Now he's talking tough on China, says we're not tough enough on China. I wish he had been that tough when the companies owned by Bain were exporting thousands of jobs to China."
The Romney campaign, meanwhile, leveled its own charges against Biden for saying that the middle class was "coming back" from ravages of the recession.
"Vice President Biden's claim that the middle class is 'coming back' couldn't be more out of touch with the reality," said Romney spokesman Ryan Williams. "Whether it's high unemployment, falling incomes, soaring tuition costs, or rising prices, middle-class families are struggling in the worst economic recovery America has ever had."