President Barack Obama is now barely edging out Mitt Romney in Florida, making the state effectively a tossup, according to a poll released Thursday by the Democratic firm PPP.

The poll shows Obama leading Romney by a single point -- 48 percent to 47 percent -- among likely voters. That's slightly narrower than in June, when another PPP survey had Obama ahead by 4 points. The June survey included a broader sampling of registered voters, including some not considered as likely to vote in 2012.

The tightened race is due largely to a sea change among independents, who supported Obama by 9 points in June, but leaned toward Romney by 7 points in the latest poll. PPP instituted a tighter 'likely voter' screen between the June poll and the latest one, which could also account for some of the difference between the two polls.

Obama's approval rating in the state has slipped 6 points since June to a net negative, with 50 percent disapproving of his job performance and 47 percent approving.

The PPP poll surveyed 871 likely Florida voters by automated phone call between July 26 and July 29. It has a 3.3 percent margin of error.

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