Speaking on CBS's "Face the Nation," Rendell faulted GOP lawmakers for votes against a measure that extended unemployment benefits and the $26 billion in aid to states that preserves jobs of teachers and public safety workers.
"The extension of unemployment benefits -- the Republican Party almost to a person voted against it, cruelly voted against it," Rendell said.
Among Republicans, Rendell noted, only Sens. Olympia Snowe and Susan Collins of Maine voted for the state aid package, which Obama signed last week.
"Who's trying to bring the economy back, and who's trying to stop it, I think, for purely political reasons?" Rendell said. "If the American people understand that, you'll see a change."
He said a poll by The Wall Street Journal showed Democrats had made significant gains. "I think there's momentum on our side," he said.
Former Republican National Committee Chairman Ed Gillespie, also on the CBS program, faulted the Obama administration and congressional Democrats for 9.5 percent unemployment and soaring deficits.
With midterm elections approaching in November, Gillespie said, "Americans are going to be looking at the economy, and they're very concerned about all of this uncertainty out there."
He also said expiration of tax cuts that became law under President George W. Bush would effectively amount to "the largest tax increase in American history."