In his article, Romney added: "The federal government should provide guarantees for post-bankruptcy financing and assure car buyers that their warranties are not at risk."
The president sought to portray himself as a longtime ally of labor, recalling his days as a community organizer working with steel workers who had been laid off when their plants shut down.
"That still drives me today," he said, reiterating a line he uses in political campaign events. "So I'll promise you this: as long as you've got an ounce of fight left in you, I'll have a ton of fight left in me."
Obama also announced that his administration will crack down on unfair trade practices worldwide, a popular theme with labor and a counterpunch to Romney's tough-on-China rhetoric. Obama was signing an executive order creating an Interagency Trade Enforcement Center.
The office will expand the administration's ability to challenge unfair trading practices in China and elsewhere and coordinate enforcement activity across several U.S. government agencies. Obama's most recent budget proposal asks Congress for millions of dollars for the new enforcement center and more U.S. inspectors in China.
Associated Press writer Ken Thomas contributed to this report.
Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.