A generic Republican candidate leads President Obama by 8 points in a hypothetical 2012 matchup, a lead that no actual GOP candidate has been able to muster.

A generic "Republican candidate" would beat Obama, 47 percent to 39 percent, among registered voters, according to a new Gallup poll released Thursday, reflecting the vulnerabilities facing the president as he gears up for reelection.

The poll found independents would break for a nameless GOP candidate by a 10-point margin, 44 to 34 percent with 22 percent undecided, a warning sign for Obama's electoral fortunes next fall.

It's the second straight month that a generic Republican leads Obama in Gallup's surveys of U.S. voters. Amid a sour mood on the economy and a massive fight in Washington, the poll suggests a bearish opinion toward the incumbent, Democratic president.

But that might not mean much, because Obama consistently leads the specific Republican candidates now running to unseat him in 2012.

Former Massachusetts Gov. Mitt Romney (R) has fared best against Obama in most polling; various state-by-state polls have suggested Romney might be leading the president in some swing states at this point of the race.

But Obama leads the putative GOP frontrunner by 6 points, according to a Quinnipiac University poll released Wednesday. Forty-seven percent of Americans would vote for Obama in a matchup against Romney, who would draw 41 percent of the popular vote. 

That's a problem for Republicans looking to nominate the best candidate to take on Obama next fall and demonstrates the disconnect between voters' enthusiasm for an alternative to Obama and the announced candidates in the campaign. It's part of the reason there have been lingering rumors of late entries into the field.

No other candidates — not Rep. Michele Bachmann (R-Minn.), former Alaska Gov. Sarah Palin (R) or Texas Gov. Rick Perry (R) — comes as close to Romney, the poll found.

The Gallup poll, conducted July 7 to 10, has a 4 percentage point margin of error.