Democrats have signaled that they intend to make Mr. Romney’s history at Bain a key part of their case against him if he wins the Republican presidential nomination. But Bain has also emerged as an issue in the Republican primary, despite the party’s pro-free market stance and business-friendly policies, reflecting the depth of public anger about the economy. At an appearance here on Sunday, Mr. Gingrich suggested that Bain’s approach was to carry out “clever legal ways to loot a company.”…

The Bain-centered campaign strikes at the heart of Mr. Romney’s argument for his qualifications as president — that as a successful executive in the private sector, he learned how to create jobs — and advances an argument that President Obama’s re-election campaign has signaled it would employ aggressively against Mr. Romney.

“His business success comes from raiding and destroy businesses — putting people out of work, stealing their health care,” said Rick Tyler, a senior adviser to the pro-Gingrich super PAC, Winning Our Future, which recently bought the film, “King of Bain: When Mitt Romney Came to Town,” after groups backing two other Republican candidates passed up opportunities to use it…

“If this is free enterprise, then conservatives should have nothing to do with it,” [Tyler] said. “It is predatory paper-shuffling. Mitt Romney was engaged in the engineered destruction of free enterprise,” including raiding workers’ pension and health care funds to finance corporate takeovers, he said.