Obama campaign spokeswoman Jen Psaki dismissed the impact of polls showing a tighter race, saying Democrats always expected the race here and elsewhere to tighten ahead of Election Day.
Illustrating the competitive nature of Ohio, no presidential battleground has been more saturated with television advertising.
The campaigns and outside groups had spent more than $141 million on TV ads in Ohio through the beginning of October, one of the highest per-person spending rates in the country. Only more-populous Florida, which has seen $150 million in ad spending, has seen a higher total.
Ads in Ohio have focused on the energy industry -- some rural, southern areas of the state rely heavily on coal -- and on China, where foreign companies are seen as competing with Ohio's manufacturing base and jeopardizing jobs.
Obama has sought to paint Romney as a plutocrat who outsourced jobs during his tenure leading the private equity firm Bain Capital.
Romney, in turn, has sharply criticized Obama's support for stricter regulations on coal and natural gas. It's seen as a way in with white working-class voters, on which his candidacy depends. "Stop the War on Coal. Fire Obama," read signs that dot the countryside of areas where Romney has held multiple events.
White blue-collar workers prefer Romney to Obama, but less so than they did Republican George W. Bush, who carried Ohio in 2004. These voters are considered still persuadable, although Romney may have hurt himself with his comment that the 47 percent of Americans who pay no income tax believe they are victims entitled to government help.
Romney's position on the auto bailout also dogs him in a state that's heavily reliant on the industry. Obama's decision to offer government support to automakers meant protection for thousands of jobs at parts and supply companies in Ohio.
Romney wrote a 2008 op-ed headlined "Let Detroit Go Bankrupt," which has become a rallying cry for Democrats. They have argued Obama's support for the bailout has had a hand in Ohio's drop in unemployment, which is now lower than the national average.
In the final weeks, both campaigns insist they have the edge in the critical ground game. That battle was playing out in the courts, as well, with Ohio's election chief saying Tuesday he will appeal a ruling that reinstates the final three early voting days in the state.
Ohio Secretary of State Jon Husted called a decision last week by a federal appeals court "an unprecedented intrusion" into how states run elections.
Husted said Friday's decision by the 6th U.S. Circuit Court of Appeals would affect how elections are run in all 50 states. The appeals court in Cincinnati affirmed a lower court ruling and returned discretion to set hours on the final three days to local boards of elections.