Correction: An earlier version of this story did not make clear that the Lawyers Committee for Civil Rights is not allied to any campaign. The story has been corrected.

Thousands of attorneys, representing the two major presidential candidates, their parties, unions, civil rights groups and voter-fraud watchdogs, are in place across the country, poised to challenge election results that may be called into question by machine failures, voter suppression or other allegations of illegal activity.

Election litigation has become an institutionalized part of campaigns since the 2000 presidential race, when Vice President Al Gore won the popular vote but Texas Gov. George W. Bush captured Florida’s 25 electoral votes (it now has 29) — and the White House — after 36 days of lawsuits, recounts and court actions. The volume of court fights triggered by contests up and down the ballot has doubled in the past 12 years, said Richard Hasen, a professor at the University of California at Irvine.

“Election law has become a part of the candidates’ political strategy,” said Hasen, the author of a new book, “The Voting Wars.”

The legal calculus has a new variable this year: Hurricane Sandy. The massive storm has hampered early voting and created concern that those in ravaged areas may have difficulty getting to the polls next Tuesday.

“If there are lingering problems, lack of power, impassable streets, closed polling places — all of those things could lead to litigation just before or on Election Day,” Hasen said.

Explore the 2012 electoral map and view historical results and demographics

With many polls — nationally and in battleground states such as Colorado, New Hampshire, Ohio and Virginia — showing a dead heat between President Obama and Mitt Romney, the two sides are putting unprecedented energy into lawyering up.

Also contributing to the litigious environment is the heightened level of distrust and skepticism about the election process that grew from the 2000 recount, experts say. Magnified and multiplied by the power of social media, those popular suspicions also could drive challenges to the election results.

Both campaigns have legal staffs that have been war-gaming the possibilities. Obama’s effort is headed by former White House counsel Robert Bauer; Romney’s is run by Ben Ginsberg, chief legal counsel for Bush’s 2000 and 2004 campaigns. Both operations declined to discuss the specifics of strategies on the record. But they indicated they are ready for contingencies on Election Day and if the race goes into “overtime.”

“We’ve retained or opened pipelines to the nation’s top experts on voting systems, registration databases, ballot design, student voting and provisional ballots,” said an Obama campaign official who was not authorized to discuss the matter and spoke on the condition of anonymity. “We’re deploying attorneys primarily to battleground states, to a wide variety of polling locations in all kinds of neighborhoods.”

Said a Romney spokesperson who also spoke on the condition of anonymity for the same reason: “We have all the resources and infrastructure we need for any potential dispute or recount.”

Other groups say they have been recruiting and training lawyers. Barbara Arnwine, president and executive director of the Lawyers Committee for Civil Rights, said last week that Election Protection, a coalition of voting rights groups, will draw on thousands of volunteers from more than 200 law firms.

David Norcross, chairman of the National Republican Lawyers Association, said many of the group’s 4,500 members are engaged. “We’re collecting all the information we need to buy airline tickets, so we know who to send where,” he said. “We have been doing our homework.”

Norcross said he has dispatched legal help at the request of the Romney campaign. Attorneys have been in Palm Beach County, Fla., where nearly 30,000 absentee ballots were unable to be electronically scanned because of a printing error. Officials are hand-copying the ballots so they can be counted. Lawyers are watching.

Legal experts say it would take an unusual confluence of circumstances to create the kind of legal donnybrook the nation witnessed in Florida: a state with a decisive number of electoral votes, a razor-thin margin separating winner and loser, and a significant number of votes unaccounted for.

“Anyone can bring a lawsuit. The question is whether you can get a judge to hear it and act on it,” said Doug Chapin, director of the Program for Excellence in Election Administration at the University of Minnesota.

Democrats say legal work this year on the front end of the election process — especially the successful challenges to voter ID laws in states such as Texas — is the most significant development.

“Contrary to some reports, there have not been far-reaching and significant changes to voter ID laws in the battleground states since 2008,” Bauer and Obama deputy campaign manager Stephanie Cutter said in a memo circulated to reporters last week. “In states like North Carolina, Iowa, and Michigan, proposed changes were rejected and did not become law; In other states like Ohio, New Hampshire, Wisconsin and Pennsylvania, legal challenges have proven highly successful in turning back unconstitutional attacks on voting rights.”

Charles Lichtman, a Democratic lawyer in Florida who is active in election issues, said that after Election Day, by and large, “it’s too late. There’s nothing that can be done for the most part once the ballots have been cast. That’s why the voter protection effort is on the front end.”

He added: “It would have to be the perfect storm. Then again, we live in the land of hurricanes.”