TALLAHASSEE — It's the nightmare scenario nobody wants to discuss: an election night result for Florida governor that's so close it demands a recount.

"Oh, no, the R-word," said Pasco County Supervisor of Elections Brian Corley. "It's going to be a close one. We're ready."

It's Florida. Anything can happen.

With polls showing Gov. Rick Scott and Charlie Crist in a virtual deadlock, both sides are making plans in case of a stalemate next week. Republicans and Democrats would mobilize armies of lawyers in a frantic search for ballots, triggering memories of the agonizing and chaotic five-week Florida recount that followed the 2000 presidential election.

"Expect the unexpected," said Sarasota County Supervisor of Elections Kathy Dent.

Florida now has nearly 12 million voters, and a 50 percent turnout would mean about 6 million votes.

A machine recount of all votes cast is required when the margin between two candidates is half of a percentage point or less. That equates to 30,000 votes with a turnout of 6 million.

Four years ago, Scott defeated Democrat Alex Sink by 61,550 votes out of 5.4 million cast or 1.2 percent. That was so close the winner wasn't known until the next morning, but it wasn't close enough for a recount.

"I think it's going to be a little bit closer than it was four years ago," predicted Miami lawyer Juan-Carlos Planas, a former state legislator who has been involved in several recount cases. "Everybody on our side is here to be sure the law is followed."

A recount must be ordered by Secretary of State Ken Detzner, a Scott appointee.

The first step, a machine recount, is a retabulation of ballots using automated machines, essentially double-checking the totals. But if that closes the gap between the candidates to a quarter of a percentage point or less, a manual recount would take place of all undervotes and overvotes, if the number of votes in dispute is large enough to alter the result.

"The pool of disputed ballots has to be greater than the difference," said lawyer Mark Herron, who advises Democrats.

An undervote occurs when a voter casts no vote in a race, and an overvote occurs when a voter chooses more than one candidate. The number of those ballots has declined since Florida abandoned punch-card ballots and their hanging chads after the 2000 debacle and switched first to touch-screen machines and later to optical scan paper ballots.

The latter change was ordered by Crist, then a Republican, soon after he took office in 2007.

The outcome also could be affected by tens of thousands of disputed votes cast by mail, overseas or provisionally and counted separately in Florida's 67 counties. Every county has a three-member canvassing board with the discretion to count or reject votes that have questionable signatures on absentee ballot envelopes.

If it's too close to call, the focus is likely to be on the three largest counties: Miami-Dade, Broward and Palm Beach. All have track records of sluggish returns and problems at the polls.

"In the big counties, it's most likely to be contentious and it's where strange things are most likely to happen," said Republican strategist J.M. "Mac" Stipanovich.

A candidate can contest an election on four grounds: ineligibility of the winning candidate to hold office; evidence of illegal votes or legal votes that weren't counted; proof that an election official was bribed; or misconduct, fraud or corruption by a canvassing board member.

That means the fight for control of the nation's biggest battleground state could easily shift to the courts, where the leading candidate would demand a quick resolution and the trailing candidate would try to expand the universe of votes.

"That's why it's so intriguing. You've got 67 separate buckets out there," Herron said. "But you've got to have enough votes to change the result in order to have a credible argument."

The Scott and Crist campaigns have designated thousands of poll watchers to monitor early voting sites and on Election Day throughout the state. In Pinellas County alone, Scott has 61 Election Day poll watchers and Crist has 50.

Democrats also say they have thousands of volunteers serving on "voter protection teams," and they are robo-calling voters and reminding them to call a voter protection hot line at (844) 358-6837 if necessary.

"We haven't seen any large issues in Florida, but we're getting a lot of good questions," said Zack Learner, a Fort Lauderdale lawyer who heads the effort and volunteered on Barack Obama's 2008 campaign in Miami.

Democrats are even using the possibility of a deadlock to raise money in the final days of the race.

In a weekend email blast, Crist's campaign said: "Whatever way it goes, the margin of victory could be a few thousand votes."

Said Scott campaign spokesman Greg Blair: "We will have every resource we need to re-elect Rick Scott."

With the stakes so high, neither candidate is likely to concede Tuesday night if the results are close.

The final results must be certified by 9 a.m. Nov. 18.

Contact Steve Bousquet at bousquet@tampabay.com or (850) 224-7263. Follow @stevebousquet.