Former Michigan Gov. Jennifer Granholm drew roars from the crowd with a fiery speech criticizing Mitt Romney.
Granholm — now a television commentator — hit Romney for his wealth by noting that the GOP presidential candidate is a car nut who ordered a car elevator for his California home.
But she said he has been less kind to U.S. auto workers, echoing a theme of the Obama campaign.
Granholm gesticulated wildly during the speech and earned some of the loudest applause of the night.
"All across America, autos are back," she added. "Manufacturing is rebounding! Why? Because when Mitt Romney said, 'Let Detroit go bankrupt,' who took the wheel? Barack Obama!"
Granholm then listed all the states in which Obama helped save auto industry jobs, which led to a wave of applause as she shouted the numbers, ending with 211,000 jobs in Michigan.
"In your car and on your ballot, the 'D' is for drive forward, and the 'R' is for reverse. And in this election, we're driving forward, not back."
Obama's campaign is centering a good part of his reelection bid on his efforts to revive the U.S. auto industry. Granholm credited Obama for the auto bailout and said, "Mitt Romney saw the same crisis, and you know what he said: 'Let Detroit go bankrupt.'"
Vice President Biden offered a tribute to Granholm in his address later on Thursday, calling her address "great."
This story was updated at 9:46 p.m.