DAVENPORT — Vice President Joe Biden stressed that revitalizing the manufacturing industry is key to rebuilding the nation’s middle class while also striking out at Republican presidential-nomination candidates’ job-creation policies Wednesday.

"I have an important message: Manufacturing is back," Biden told a crowd of supporters and employees of the PCT Engineered Systems on Wednesday. "It’s good news for America. It’s even better news for America’s middle class."

Experts said the manufacturing sector has added more than 400,000 new jobs nationwide since 2010, with Iowans working in more than 15,000 of them.

The increase in manufacturing jobs shows the economic importance of the industry, said Jacey Wilkins, the director of communications for the Manufacturing Institute.

"Manufacturing is the true wealth creator," she said. "It drives economic development in states and nationally. It creates more value and has a higher multiplier effect than any sector of the economy."

Biden also took a jab at the policies of Republican candidates Rick Santorum and Mitt Romney.

"The actual notion that manufacturing in this country is dead is dead wrong," he said. "And we have to maintain this momentum … one thing that will bring this momentum to a screeching halt is turning over the keys to the White House to Santorum or Romney."

Biden accused Romney of outsourcing American jobs as CEO of Bain Capital during the 1990s and advocating for outsourcing as the governor of Massachusetts. Santorum’s views on outsourcing and insourcing jobs, Biden said, have been "inconsistent."

University of Buffalo distinguished political-science Professor James Campbell said Biden’s claims were interesting, because the Obama administration employs a free-trade policy that includes outsourcing as well as insourcing.

"If we have a strong economy and have advantages in the productions in some goods and services, then some companies will stay here," he said, noting tax incentives. "If we have a tax system that’s too high, then companies vote with their feet, and they’ll leave."

Tim Hagle, a University of Iowa associate professor of political science, said sometimes companies have no choice but to export jobs.

"No candidate is going to advocate for outsourcing jobs, but on the other hand, if you have a company that is failing, what do you do?" he said. "[Democrats] say Romney is in favor of outsourcing, but that isn’t really accurate — sometimes it’s the lesser of the two evils."

Romney’s policies state that he supports increased free-trade agreements and more open markets beyond American borders, according to the candidate’s website.

Amanda Henneberg, a spokeswoman for the Romney campaign, said the Obama administration has done more to "devastate the middle class than any in modern history."

"Under President Obama’s leadership, over 800,000 fewer Americans have jobs, home prices have plummeted, and gas prices have hit record highs," she wrote in an email. "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."

The Daily Iowan was unable to reach a representative of the Santorum campaign Wednesday evening.

Experts said Biden’s visit also served as a strategic campaign stop before the November general election.

"The idea of coming to Davenport is to show, ‘Well, here is a plant that did well during [Obama’s] term,’ " Hagle said. "It’s not all gloom and doom. This is a success story."

Biden’s stop was the third in a series of speeches which began two weeks ago.