"He promised us the same things he's promising the United States," a man whom the group says formerly worked at a Kansas City steel company says of Romney in the ad.
"He'll give you the same thing he gave us: nothing," the ad continues. "He'll take it all."
The company, GST Steel, went bankrupt and closed in 2001, eight years after Romney's private equity firm, Bain Capital, purchased it, according to a Reuters report on the bankruptcy which is cited in the ad.
Romney left the company in 1999, but has continued to benefit through the company. His campaign has noted that Romney's finances are held in and managed by a "blind trust."
GST Steel, which became GS Technologies, is the same company used in a similar criticism of Romney's business record by the Obama campaign, which distributed a two-minute video featuring other employees of the company on Monday.
Federal campaign regulations prohibit coordination between campaigns and super PACs.
The $4 million buy will air in Colorado, Florida, Ohio, Pennsylvania, and Virginia between now and the end of May, a source familiar with the buy told CNN.
The Obama campaign buy is much smaller in scope: the two-minute ad is to air during evening newscasts on Wednesday.
A Republican ad-tracking source told CNN on Monday evening that $64,000 of airtime has been purchased in five battleground states, and a source with knowledge of the buy said it would total less than $100,000.
This comes months after Romney's opponents - candidates and super PACs alike - criticized him on the stump, in debates, and in millions of dollars of television ads for the results of his work at Bain.
The Priorities USA ad, like several before it, say that Romney's firm managed to profit handsomely while some of the companies they purchased went underwater.
"If we lost, they made money," Pat Wells, the worker featured in the Priorities USA ad, said. "If we survived, they made money."
In response to the Monday ad produced by Obama's campaign, Romney spokeswoman Andrea Saul said, "Mitt Romney helped create more jobs in his private sector experience and more jobs as governor of Massachusetts than President Obama has for the entire nation."
Her statement also criticized Obama's handling of the economic stimulus funds, which was used " to reward wealthy campaign donors with taxpayer money for bad ideas like Solyndra," while many Americans remained unemployed, she said.
(CNN's Paul Steinhauser, Kevin Bohn, Kevin Liptak, and Gregory Wallace contributed to this report)
(video report: Jim Acosta, CNN)