WASHINGTON -- A presidential race that has been neck-and-neck for months suddenly isn't.

In the week after the political conventions ended, President Obama has opened the most significant, sustained lead in the daily Gallup Poll since Mitt Romney emerged as the Republican nominee last spring. Disappointing unemployment statistics released last Friday haven't stemmed Obama's rise, and Romney's sharp criticism of the president in recent days during the unfolding crisis in Libya has opened a new line of partisan attack against the challenger.

With 53 days and three presidential debates to go, strategists in both parties say there's time for Romney to recover lost ground, especially with an electorate deeply dissatisfied with the direction of the country and the state of the economy. But even some Republican political analysts warn that the former Massachusetts governor faces a political landscape that has become steeper as the campaign heads into the home stretch.

The Gallup Poll showed Obama leading Romney 50%-44% Thursday among registered voters. A Fox News poll Wednesday also had Obama ahead, 48%-43%, among likely voters.

The two candidates had been locked within 2 percentage points of each other in the daily Gallup survey since July. Neither had held a lead of as much as 5 points since June.

"You don't have a path to victory if the trajectory of the campaign continues in the direction it's been since the opening night of Romney's convention," says Steve Schmidt, a top campaign strategist for Republican John McCain four years ago. He likens the situation to 2004, when then-president George W. Bush used the Republican convention to boost his approval rating and define his opponent.

In 2008, however, McCain's narrow lead after the conventions disappeared after a week.

"It's possible you get a real bounce out of the convention, which has happened for Obama," says Frank Newport, editor in chief of the Gallup Poll, "but whether that resets the campaign permanently or begins to dissipate is something we'll need to wait and see into next week."

At their convention, the Democrats succeeded less in burnishing Obama's credentials than in tarnishing Romney's, says Lawrence Jacobs, director of the Center for the Study of Politics and Governance at the University of Minnesota. They focused on the administration's successes in killing Osama bin Laden and bailing out the auto industry, steps Romney had opposed or downplayed.

"This risk of changing horses midstream was the main message that the Democrats delivered with almost every speech," Jacobs says. "Then Romney's own behavior gives further evidence and raises the question, â??Is he ready?'

Romney advisers argue the fragile economy remains an overriding concern that will dog the incumbent; the Federal Reserve on Thursday announced steps to spur employment. "It's essentially the same race we had three weeks ago," Romney pollster Neil Newhouse said in an interview, saying Obama's bounce was "melting" already. "Voters are polarized; they think the country is off on the wrong track; they disapprove of the job the president is doing. It's a race that's going to go down to the wire."

The Obama campaign counsels caution, too. "There are debates coming up and, as we saw this week, there are these external events that you can't even predict that intrude on the process," Obama strategist David Axelrod said. "You'd be foolish to be too giddy about where things are. That said, I like where things are."

Axelrod said the Democratic convention succeeded in making the case to undecided voters and in energizing core supporters. The Obama campaign in August managed to raise more money than the Romney campaign for the first time since April, a development that could reflect a revival in Democrats' lagging enthusiasm.

USA Today