Apart from the battle for the state’s prized electoral votes and aside from the roiling campaign for a U.S. Senate seat, Florida is experiencing a high-stakes political contest unlike any it has ever seen.

It involves the most determined effort ever to defeat the reelection bids of three members of the state Supreme Court.

A loosely organized Internet campaign against the court two years ago has been fortified by the conservative group Americans for Prosperity, founded by billionaire activists Charles and David Koch. And then came the surprise announcement that the Republican Party of Florida had decided to oppose all three justices, an unprecedented move in the nonpartisan vote.

Party leaders said that “collective evidence of judicial activism” showed the jurists to be liberals who are out of touch with the public.

Opponents point to the court’s death penalty decisions and a ruling that kept an “Obamacare” referendum off the 2010 ballot. But the justices’ supporters say an effort is underway to pack the court with new appointees and deliver Republicans the only branch of state government they don’t control.

Follow President Obama, Mitt Romney, their running mates and spouses on the campaign trail

Justices Barbara J. Pariente, R. Fred Lewis and Peggy A. Quince have faced voters twice before and easily retained their jobs. But this year they have hired consultants with the $1.3 million raised on their behalf, filmed commercials and hit the road for appearances. Because they can’t sell themselves, they try to sell the nonpartisan selection system that got them here — a system they say is under attack.

“The people of Florida deserve a judicial branch that is not beholden to big guys or little guys, to big money or no money, to agendas of any kind,” Lewis told law students at the University of Florida last week, coming the closest of the three to delivering the judicial equivalent of a savvy political sound bite.

“We’re not politicians,” Pariente said.

The fight in Florida is different from judicial campaigns that have drawn notice in other states, where trial lawyers on one side and big business on the other have turned partisan elections into multimillion-dollar affairs.

And unlike the three Iowa justices who were voted out in 2010 after ruling in favor of same-sex marriage, the Florida justices have made no landmark decisions.

In fact, said Alex Villalobos, chairman of Democracy at Stake, a group defending the justices, “nobody has a clue what the Supreme Court does.” But, he said, the court is well-known to the state’s powerful interests.

“Some very smart people have figured out that it can be a lot cheaper to change policy in a state like Florida by taking out the justices rather than by taking on the governor or changing the numbers in the legislature,” he said.

It is clear that this campaign against justices is different from one two years ago, when the Florida chapter of Americans for Prosperity got involved. While not taking a position on whether the justices should be voted out, the group spent $100,000 on a Web site and one night of television commercials criticizing the court’s decision to keep a referendum on President Obama’s health-care legislation off the ballot because the wording was misleading.

Quince, who was appointed in late 1998, said she was “surprised and disappointed” by the Republican Party’s executive board vote to oppose the justices. The system for approving justices “has been in place in Florida for almost 40 years,” she said in an interview. “Never has a political party ever taken a position.”

Added Pariente: “Do Floridians — or anybody — want a more politicized judiciary?”

Florida stopped electing justices in the 1970s after a scandal led to the resignation of two justices. A third, Joseph Boyd, avoided impeachment only by agreeing to have a psychiatric exam; he is famous for later boasting that he was the only officeholder in Tallahassee to be certified sane.

Voters amended the state constitution to imposed a merit retention system, in which the governor chooses a justice from a list compiled by a nominating commission. After a six-year term, the justice stands for a retention vote.

Lenny Curry, who chairs the Republican Party of Florida, said the opposition “came from the party’s grass roots — this was not part of a strategic plan.” Tea party members, he said, were particularly upset by the court’s decision on the health-care referendum (which was rewritten by the legislature and will appear on next month’s ballot).

“I’m really surprised by the backlash” against the party’s decision, Curry said, adding that justices should expect that the public will evaluate their actions.

Florida Democratic Party Chairman Rod Smith notes that Republican state legislators tried to expand the court to 10 members to give Gov. Rick Scott (R) three new appointments. When that failed, he said, they decided to oppose the justices up for retention.

“Come on, it’s a ruse,” said Smith, a trial lawyer. “This is about court-packing.”

Defend Justice from Politics, a group supporting the justices, has spent nearly $1.5 million on them, more than their individual campaigns.

“We know, obviously, that the Koch brothers weighed in with some media,” Pariente said. She added that voters should wonder, “What do you, from out of state, want with our state Supreme Court? I’d be very concerned if I was a voter.”

Slade O’Brien, the Florida state director of Americans for Prosperity, said interest in the court is homegrown. “If the Koch brothers even know about this, it’s because they read about it in the newspapers,” he said.

He said researchers for his organization found “what we consider to be judicial activism, legislating from the bench,” in a number of cases involving the death penalty, school vouchers, plaintiffs’ rights and a property rights decision.

The groups, however, are facing head winds in making the case that the justices are out of step. A Florida Bar poll of its members who practice before the court gave all three approval ratings of about 90 percent. And a study commissioned by the conservative Federalist Society found nothing to support a charge of judicial activism.

“There does not appear to be a pattern of unprincipled decision-making by any of the justices of the Florida Supreme Court,” wrote Elizabeth Price Foley, a constitutional law professor at Florida International University.

There are voting patterns that seem to be based on ideological leanings, she said, but that is “true with all courts, not just Florida’s Supreme Court. Judges, after all, are human, not computers.”