But in a troubling sign for the Republican nominee, his lead in Florida slips into a dead heat when third-party candidates, including Libertarian Party nominee Gary Johnson, are added into the poll. And among all registered voters — not just those expected to vote — the present owns a 52-46 percent advantage.

The CNN poll of Florida was released the same day as a survey from Democratic pollster Public Policy Polling that gave Obama a single-point advantage in the state, by a 49-48 percent margin. But Republicans remained optimistic about their prospects in the state, noting that many voters had made up their minds — and voted early — over the past few weeks, as Romney led in the state. Of those likely voters surveyed in the CNN poll, 94 percent said they had made up their mind.

Republicans also argued that they were encouraged by early voting reports from Florida.

"Early vote and absentee returns combined are essentially even between the GOP and Dems, whereas in 2008 Democrats had a seven point advantage," Republican National Committee spokesman Tim Miller said in a memo released to reporters Monday, adding that Obama had won the state by less than three points in 2008.

In North Carolina, Romney also saw encouraging news on the economy — expected to be the single most important issue among voters. Romney led 52-42 percent among those surveyed by Elon when asked which candidate they trusted more in handling the economy.

Nevertheless, Obama was given a lead on handling foreign relations by an identical margin, and led Romney 47-45 percent when voters were asked who better shared their values.

In a conference call earlier Monday with reporters, Obama senior adviser David Axelrod expressed confidence in the campaign's ability to stay competitive in the Tar Heel state, which Obama won by fractions of a percent in 2008.

“We really believe North Carolina is within our reach," Axelrod said. "Everything that we see points to a real possibility there."