(CBS)-- With polls showing President Obama and presumptive Republican nominee Mitt Romney neck-and-neck nationally, new surveys by NBC/Marist are out showing the president with a slim advantage in the crucial battleground states of Florida, Ohio and Virginia.
The surveys, conducted May 17-20, show Mr. Obama leading Romney by four points, 48 percent to 44 percent, in both Florida and Virginia, slightly outside the polls' 3-point margin of error.
In Ohio, the president leads Romney 48 percent to 42 percent, according to the poll.
A majority of voters in all three states expressed a sense of optimism regarding the economy, saying they believe the worst is behind us with regard to the recession. Still, 40 percent or less said they expect the economy to improve in the next year.
The Marist poll contrasts with one released Wednesday by Quinnipiac, which showed Romney up six points, 47 percent to 41 percent, in the crucial battleground state of Florida.
The Marist survey also shows Mr. Obama with an advantage among women voters. According to NBC, Romney leads the president narrowly among men in all three states, but in Florida and Virginia, Mr. Obama leads Romney among women by 10 points. In Ohio, he has a 12-point edge over Romney among women voters.
Senate Democrats enjoy similar advantages in these states, according to the survey. In Ohio, Democratic candidate Sen. Sherrod Brown leads Republican Josh Mandel by 14 percent, 51 percent to 37 percent, among registered voters. In Virginia, Democrat Tim Kaine edges out Republican George Allen by six points, 49 percent to 43 percent, and in Florida, Democrat Bill Nelson has a four-point advantage over Republican Connie Mack, with 46 percent support to 42 percent support.
While the NBC/Marist poll shows the president with a slight lead in these three key battleground states, NBC notes that his lead in Ohio and Virginia has diminished since March, when he led Romney by 12 points in Ohio and by 17 points in Virginia.
Moreover, a Quinnipiac poll released Wednesday showed Mitt Romney edging Mr. Obama out by six points in Florida.
All three races are expected to be down-to-the wire this November, and each potentially has the power to tip the delegate scale toward either Mr. Obama or Romney.