Joe Biden (Creative Commons)

Vice President Joe Biden went on the attack for the first time Thursday, lambasting President Barack Obama's GOP rivals, while defending the auto bailout in front of a raucous United Auto Workers crowd in Ohio.

The strategy marked a new phase in the campaign, as GOP candidates continue to slough through their nominating process. 

"If you give any one of these guys the keys to the White House, they will bankrupt the middle class," said Biden in the key battleground state. 

The speech was the first of four in the coming weeks for the vice president, and came hours before the release of a documentary on Obama's presidency. 

According to CNN, Biden will continue his campaign in Florida next week, and will defend the White House's stance on Medicare. Biden will also campaign in Iowa, New Hampshire, Virginia and Pennsylvania. 

According to CNN:

"Biden kicked off the most visible effort to date of the Obama campaign to win a second term in the November general election. The vice president went after the Republican candidates by name, something the president has not done so far…"

"I want to tell you what is real bankruptcy," said Biden. "The economic theories of Gingrich, Santorum and Romney."

Time magazine called the VP's first campaign speech "no-holds-barred political rhetoric, well timed and placed in North Ohio."

"There is no doubt about what the Obama campaign is doing here. They are mounting a massive persuasion campaign to convince the country of something it does not yet believe," reads the article.

The New York Times called the speech "a working-class appeal."

"The verdict is in," Biden said. "President Obama was right, and they were dead wrong."

Watch Biden's speech below: