Ohio

"... based on the data so far this year, Ohio has been slightly Democratic-leaning relative to the country as a whole. That reflects a reversal from the usual circumstances. Normally, Ohio — though very close to the national averages — leans Republican by two points or so.
...
It’s by no means impossible that Mr. Romney could win the Electoral College despite losing Ohio, but it would be an uphill battle."

http://fivethirtyeight.blogs.nytimes.com/2012/07/27/july-27-ohio-polls-show-trouble-for-romney/

If Romney’s ads go positive, he may gain independent voter support

“…the Republicans are doing the exact wrong thing by making 90 percent of their ads attacks on Obama. Although voters always say this but rarely mean it, they really do want Romney to go positive. They are interested in learning about his accomplishments (or lack thereof), especially during his term as governor.”

http://www.realclearpolitics.com/articles/2012/07/25/to_move_polls_romney_needs_to_go_positive_114903.html

Obama continues to take chances:  pro-choice ads begin airing in battleground states

“The commercial … is airing in Florida, Iowa, North Carolina, New Hampshire, Virginia, Nevada and Ohio. It will start running in Colorado on Monday.”

http://politicalticker.blogs.cnn.com/2012/07/26/obama-campaign-airs-second-ad-hitting-romney-on-abortion/