Asheville, North Carolina (CNN) -- Mitt Romney's campaign seized on what Republicans called a "stunning admission" made Tuesday by Vice President Joe Biden when he said the middle class "has been buried" the last four years, putting the Obama campaign on defense.

During a campaign event in Charlotte, North Carolina, the vice president reiterated recent attacks against his Republican opponents: claiming that Mitt Romney and Paul Ryan's economic plans would raise taxes on middle class families.

"This is deadly earnest," Biden said. "How they can justify, how they can justify raising taxes on the middle class that has been buried the last four years? How in the Lord's name can they justify raising their taxes? We've seen this movie before."

Republicans have taken off on part of those comments.

A tweet from Romney's account read: "Agree with @JoeBiden, the middle class has been buried the last 4 years, which is why we need a change in November."

A spokesman for his campaign went further.

"Vice President Biden made a stunning admission today and we couldn't agree more: the middle class has been 'buried' under the last four years of this President's policies," wrote Curt Cashour, the Virginia Communications Director for the Romney campaign.

"Under President Obama, the middle class has suffered from crushing unemployment, rising prices and falling incomes. They can't afford to be 'buried' for four more years. Mitt Romney and Paul Ryan will take our nation in a new direction and are offering exactly what hardworking families need -- real reforms for a real recovery."

Though Biden's comments seemed intended to echo past comments -- that middle class families have been hit hard in the trouble economy -- they nonetheless forced the Obama campaign to go on defense.

"As the Vice President has been saying all year and again in his remarks today, the middle class was punished by the failed Bush policies that crashed our economy - and a vote for Mitt Romney and Paul Ryan is a return to those failed policies," an Obama campaign official said. "With more than five million private-sector jobs created since 2010, the Vice President and President Obama will continue to help the middle class recover and move the nation forward."