(CNN) – Vice President Joe Biden returned to the campaign trail Wednesday to deliver a stinging critique of leading Republican presidential candidate Mitt Romney before an audience of manufacturing workers in Iowa.
"Mitt Romney has been remarkably consistent - as an individual investor, a businessman, as governor of Massachusetts, and now as a candidate for president ... consistently wrong," the vice president said.
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The event, held at an engineering plant in Davenport, was the third in a series of speeches the vice president is delivering in key battleground states as the president's re-election effort shifts into a more publicly combative phase seven months before Election Day.
The vice president also met with a private gathering of grassroots supporters in Sioux City Wednesday.
The president himself continues to refrain from attacking any of his potential Republican opponents directly. But Biden - long recognized as an effective communicator with blue-collar voters especially - has increasingly let loose. The No. 1 target is Romney, who the vice president has painted as a ruthless capitalist eager to outsource middle class jobs.
"He vetoed a bill passed by the Massachusetts legislature that would have stopped the state from outsourcing contracts overseas," Biden said of Romney's time as governor.
The Obama campaign has so far dispatched Biden to speak before groups largely favorable to the president in 2008: two weeks ago he rallied United Auto Workers in Ohio, while last week he addressed seniors in a Florida retirement community. The president carried Ohio, Florida and Iowa in 2008, though only by single digits in each instance.
Biden's speech in Davenport perhaps constituted his sharpest critique of the GOP's economic philosophy; yet, he also told voters they face a stark choice next November.
"Look folks, we have a choice in this election: Between our philosophy that believes manufacturing is central to our economy, and their philosophy that scoffs at it," Biden said. "Between our philosophy that says there is nothing 'out of touch' about fighting for the future of the middle class by creating manufacturing jobs ... And their philosophy that says if the folks at the top do well, that's good enough."
The Romney campaign hit back at Biden, saying he is "part of an administration that has done more to devastate the middle class than any in modern history."
"Under President Obama's leadership, over 800,000 fewer Americans have a job, home prices have plummeted, and gas prices have hit record highs. With that kind of record, it's no surprise that the Obama White House has taken to attacking a proven job creator like Mitt Romney," campaign spokeswoman Amanda Henneberg said in a statement.
Obama will return to the campaign trail Friday, attending two large fundraisers in Vermont and Maine.