Mitt Romney, in Ohio with coal miners, slammed the president for toughening regulations.
"If you don't believe in coal, if you don't believe in energy independence for America, then say it," Romney said.
Wind is one alternative the president pushed.
"The wind industry now supports 7,000 jobs here in Iowa...That's worth fighting for. That's what's at stake right now," Mr. Obama said.
Both campaigns are framing the election as a choice on big issues.
Romney raised Medicare in a new ad, accusing President Obama of cutting $716 billion from the program.
The cut affects doctors and hospitals, not seniors' benefits.
Romney running mate Paul Ryan's Medicare plan would keep those cuts and, in ten years make private coverage an option.
Ryan was in Colorado Tuesday, where he blasted President Obama's handling of the economy as a "failure of leadership."
In Virginia, Vice President Biden charged Romney would drop tough new rules on big banks, saying "Unchain Wall Street? He's going to put you all back in chains."
Staffers quickly clarified Biden meant deregulation would hurt the middle class.