The video: Speaking at a campaign stop in Charlotte, N.C., on Tuesday, Vice President Joe Biden inadvertently put his foot in his mouth once again, this time while slamming Republican tax policies. Under a Romney-Ryan White House, Biden charged, taxes for the rich would be slashed, hurting an already-overburdened middle class. "This is deadly earnest," a fired-up Biden said. "How they can justify — how they can justify raising taxes on the middle class that's been buried the last four years. How in Lord's name can they justify raising their taxes with these tax cuts?" (Watch the video below.) The big problem? "Barack Obama has been president the last four years, and Biden has been vice president," says Daniel Halper at The Weekly Standard.

The reaction: Republican nominee Mitt Romney quickly seized on Biden's gaffe with the following tweet:

A spokesperson for the Romney camp elaborated

"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."

A spokesperson representing Team Obama parried

"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. 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."

Many liberals were quick to back the Obama line. Here's The Washington Post's Greg Sargent:

Judge for yourself: