Romney’s strength: The economy — the top issue for more than 60 percent of the Florida electorate, according to exit polling. Of these economy-first voters, Romney beats Obama by 6 percentage points. By 51-46 percent, voters believed that Romney would be better than Obama in handling the economy.

Voters also believed Romney was slightly more likely than Obama to share their values, be a strong leader or have a better vision for the future.

Romney also persuaded some voters that, like Obama four years ago, he is the candidate who can bring about change.

“We need a better change,” said Samantha Gentile, a 20-year-old independent who voted Tuesday at St. Gregory’s Church in Boca Raton.

“We need an economic change,” Gentile said. “We need jobs.”

Florida voters didn’t completely blame Obama for the nation’s economic woes; 51 percent said it was President George W. Bush’s fault and 42 percent said Obama.

Gentile’s remarks stood out, in part, because of the T-shirt she wore that openly advertised her support of gay marriage, which Romney opposes. Gentile said she also favors abortion rights, while Romney is opposed.

The exit polls indicated that Gentile was in the minority for those in her age group. Obama carried young voters, while he lost older voters to Romney, the exit polls showed. Voters thought Obama was better than Romney by 50-46 percent, when it came to managing Medicare. Also, the poll showed, 57 percent of Florida voters believed that taxes need to be increased on the wealthy —a position that blunted Romney’s attack against Obama as a tax raiser.

Obama fared well on an all-important question for Florida voters: Are you better off now than four years ago? Only 34 percent said no, and more than 83 percent of them were Romney voters.

Both sides slung considerable mud at each other. In all, including the U.S. Senate race, about $180 million in ads were spent in Florida. Many of them were negative. Obama spent a huge sum attacking Romney in the summer to drag down the Republican’s poll numbers. Romney surged briefly after an October debate that Obama lost.

It could take days for the final results of the election to be clear. In Miami-Dade, voters remained in line in some precincts until well past midnight.

The close race could easily trigger a recount under Florida law, which automatically kicks in when any race is decided by a margin of one-half of one percent or less.

If 9 million people vote in Florida — a plausible figure, given reports of heavy turnout around the state — that means there could be a recount if the presidential vote is decided by 45,000 votes or less.

In a recount, all ballots are submitted again into the tabulating machines to recount the votes. If the recount yields a margin of one-quarter of one percent or less, the local canvassing boards must then perform a manual recount to examine so-called “undervotes” and “overvotes” — ballots that recorded no vote for president, or multiple votes for president.

Any recount must be completed within nine days from the day it is ordered by the Secretary of State. However, state law also says any recounts must be completed within 12 days of Election Day.

But, just as in the 2000 recount, there are tensions between the state and federal law: Elections officials still must collect absentee ballots cast overseas for some 10 days after Election Day. So overseas ballots could trickle in through Nov. 16, with a recount deadline of Nov. 18.

In 2008, more than 97,000 absentee ballots were cast by overseas Florida voters.

For those who have blotted it from their memories: The 2000 contest between George W. Bush and Al Gore was decided by just 537 votes in Florida.

Miami Herald staff writers Amy Sherman and Kathleen McGrory contributed to this story.