The state is especially critical for Romney.
With his paths limited toward the 270 electoral votes needed to win the White House, Romney's chances are far more difficult if he doesn't claim Florida's cache of 29. That explains why he is starting to pour even more money into television commercials here now that he has access to general-election funds. Both campaigns expect Republicans to outspend Democrats on the airwaves in the final weeks of the race in a state that already has seen each side spend roughly $60 million on TV ads.
The situation in Florida - and the campaigns' anxieties about it - reflects the overall state of the presidential race.
A new smattering of polls shows Obama ahead by several percentage points in key states including Florida, Ohio, and Virginia, as well as nationally. The clock is ticking toward November, Obama clearly has momentum on his side, and Romney faces dwindling opportunities to change the race's trajectory.
Without Florida, Romney would have to win all of the states that are leaning his way, as well as all of the others that Obama won four years ago but now are too close to call - Ohio, Virginia, Iowa, Colorado, Nevada, and New Hampshire - and still pick up two more electoral votes elsewhere, in states that are even more difficult. The uncertainty of Florida partly explains why Romney now is making a play for Wisconsin. That state, which offers 10 electoral votes, has voted for Democrats for decades, but the GOP has seen down-ballot success there lately and Romney's running mate, Paul Ryan, lives there.
Obama already has far more states - and, thus, electoral votes - in his likely-winners column. Because of that edge, he can hold the White House without Florida as long as he wins most of the other toss-up states. His standing has suffered here along with Florida's economy, four years after he won the state by cobbling together a coalition of Hispanics, African Americans, and independents to go with other Democrats.
This year, undecided voters, and those not entirely sold on their candidates, may well tip the balance here. Few seem hot on either contender. And most say the economy is Issue No. 1 in a state whose 8.8 percent unemployment rate is among the highest in the nation.
Kathy Belcher, a Democrat from Apopka, is leaning toward Obama but says she would be willing to give Romney a chance if he offered more details on the economy and health care.
"It seems with Obama, people are getting a handout," Belcher said. So, she added, she is considering voting for Romney if he can assure her that won't happen under him. "But that hasn't happened."
Donna Sprenkle, a registered Republican from Apopka, plans to vote for Romney - reluctantly. She doesn't think he has explained well enough how he would fix the economy.
"I know somebody just can't overnight bring it back," Sprenkle said.
These are among the persuadable voters Obama, Romney, and their top surrogates are courting as they make campaign stops in Florida. The latest public poll - an NBC News/Wall Street Journal/Marist Poll released Thursday - shows Obama with a 49 to 44 percent advantage over Romney.
Democrats caution that the numbers could change. And some party insiders who expect the race to come down to three states - Florida, Ohio, and Virginia - say Florida still concerns them the most given the state's unpredictable voting patterns. Republican George W. Bush won the state twice.
"Even with all of the missteps by Romney, Obama hasn't been able to put it away," said Steve Vancore, a Florida-based Democratic pollster. "There's still time for this to change."
Democrats worry that their efforts could be hampered by the legal wrangling in Florida over early-voting and voter-registration laws. Voters across the state will probably be limited to no more than eight days of early voting, down from 14 in 2008. Obama's edge among people who voted early was one of his keys to victory.
The state's GOP-led legislature and Republican governor also instituted new requirements on voter-registration drives, including a 48-hour deadline for turning applications in to election officials. A federal judge recently blocked that provision, but some Democrats say it had already slowed their registration efforts.