A new National Public Radio poll, which had President Obama leading Mitt Romney 51 percent to 44 percent four weeks ago, now has Mitt Romney on top, 48 percent to 47 percent, with the Republican benefiting from his debate performances.

The poll found that among likely voters, 34 percent said Romney's debate performances made them more likely to vote for the challenger while 28 percent said they now are more likely to vote for the president. Among critical independent voters, though, Romney won big, with 37 percent saying they are now more likely to chose him compared to 21 percent for Obama.

But Democratic pollster Stanley Greenberg and Republican pollster Whit Ayres found that Obama leads by 4 points in the 12 battleground states that appear ready to pick the winner for the rest of the country next Tuesday. And they suggest that Romney's post-debate surge has "stalled."

The duo surveyed 1,000 likely voters nationwide with an over-sampling in 12 battleground states: Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin. The poll was conducted Tuesday through Thursday (October 23-25). The margin of error is 3 percentage points for the national sample, and 4.5 percentage points for the smaller subsample (462 respondents) in the battleground states. The sample was 35 percent Democrat, 31 percent Republican.

Ayers said that Romney is doing particularly well among independent voters. According to NPR, "most of the gains for Romney have come from independents, who went from favoring Romney by a few points before the debates to favoring him 51% to 39% after the debates."

Ayres added, "So were it not for the debates, I think Obama would be cruising to a victory right now. Because of the debates, this is going to be an incredibly close election."

Romney also beat Obama as the candidate best prepared to handle the issues of jobs, the deficit and taxes, but Obama won on more issues: health care, Medicare, foreign policy and national security.

What's more, those polled said that Obama, by a 55 percent to 44 percent margin, has spelled out a clear agenda for the nation.