Obama framed her husband's agenda as an effort "to restore that basic middle-class security," citing his push for health-care reform, improved employment numbers and a bailout of the American auto industry.
"We believe that folks shouldn't go bankrupt because somebody gets sick," she said. "They shouldn't lose their house because somebody loses a job."
Obama didn't mention Romney by name or target his policies or politics. That job was left to Mayor Nutter, who accused Romney of pushing an "agenda for the wealthy, not for the workers."
Speaking before Obama, Nutter accused Romney of failing on the key issue of job creation as governor of Massachusetts.
"As a candidate for president, Mitt Romney promises more of the same," Nutter said. "Working families here in Pennsylvania cannot afford the no-growth Romney economics."
A new Daily News/Franklin & Marshall College Poll on Wednesday showed Obama leading Romney 48 percent to 36 percent among registered voters in Pennsylvania with 12 percent undecided.
But one measure of voter enthusiasm may show signs of stalling for Obama in Philadelphia.
The City Commission on Wednesday reported that requests for new voter registrations are running at about one-fourth of what they were during this period in 2008, when they were swamped with applications from people eager to support Obama's first bid for the White House. n
Contact Chris Brennan at 215-854-5973 or email him at firstname.lastname@example.org. Follow him on Twitter @ChrisBrennanDN and read his blog, PhillyClout.com.