Buoyed by a string of recent polls suggesting his lead in Ohio is nearing double digits, President Barack Obama crisscrossed the crucial battleground state on Wednesday and sharpened his attacks on rival Mitt Romney's "47%" comments.

"I don't believe we can get very far with leaders who write off half the nation as a bunch of victims, who never take responsibility for their own lives," Obama told a crowd of more than 5,000 at Bowling Green State University. "I've got to tell you, as I travel around Ohio and as I look out on this crowd, I don't see any victims. I see hard-working Ohioans."

The recently added attack line to the president's stump speech comes as polls in the Buckeye State and other key swing states suggest Romney's controversial comments - made at a May fundraiser but only surfacing last week -- about Obama supporters being dependent on government are taking a toll.

A CNN poll of recent surveys of Ohio voters shows the president now seven points ahead of Romney. A week ago, the margin was five points.

Obama also stopped at Kent State on Wednesday. At both stops he took pointed jabs at Romney over the issue of business and jobs lost to China - a campaign boogeyman that resonates well in manufacturing states like Ohio.

"He's been talking tough on China, have you been hearing this?" Obama said at his first event. "It sounds better than talking about all the years he spent profiting from companies that sent our jobs to China."

Ohio is one of the most sought-after prizes in the election with 18 electoral votes. This was Obama's 13th visit to the state this year and he will return in one week -- immediately following his first debate with Romney in Denver.

No Republican has managed to win the White House without winning Ohio.