Obama up in Ohio; tied in Fla., Va.

President Obama retains a lead in Ohio, but his race with Republican Mitt Romney has tightened in the key states of Florida and Virginia, says a new poll.

Obama leads Romney 51%-43% in Ohio, according to the NBC News/Wall Street Journal/Marist College Poll.

The two candidate are locked in a statistical tie in Florida, where Obama leads 47%-46%, and in Virginia, where the president is ahead 48%-46%.

Last month, Obama had healthy leads in both states.

"Things have returned in Florida and Virginia to the kind of closeness we've been seeing earlier in the campaign," said Lee Miringoff, director of the Marist Institute for Public Opinion, which conducted the poll.

He added. "Not so in Ohio."

In the Buckeye State, the pollster said, Obama's advantage "continues to be fueled by a wide lead among women and a close contest for the support of men."

Florida has tightened in the last month because "independent voters have flipped from supporting Obama to now favoring Romney," Miringoff said.

Virginia also appears to be a tight race on many levels.

"Not only do Obama and Romney have similar support among likely voters in the state, their backers are equally enthusiastic and committed to their choice," Miringoff said.