TALLAHASSEE -- As the secretive campaign against the three Florida Supreme Court justices up for merit retention took shape Monday, one of the targeted justices warned that the future of the state’s independent judiciary was under threat.

"This is the most stressful time I’ve ever experienced in my life,’’ said Justice R. Fred Lewis at a meeting of the Hillsborough County Bar Association. “There is an entire branch of government to protect and defend. We cannot sacrifice fairness and impartiality and the court system to political whims."

Lewis’ remarks came three days after the Republican Party of Florida announced it will oppose him and Justices Barbara Pariente and Peggy Quince because of their "activist" and liberal views.

On Monday, Americans for Prosperity, the conservative advocacy group affiliated with the Koch brothers announced a political campaign they have been developing for months to highlight the judicial records of the justices. Starting Tuesday, the group will run television ads across the state chastising the justices for ruling against a 2010 proposed constitutional amendment intended by the Legislature to counter President Barack Obama’s Affordable Health Care Act — the one Republicans dubbed ObamaCare.

“We’re not advocating for the election or defeat of any of the justices what we’re attempting to do is call more attention to them advocating from the bench,’’ said Slade O’Brien, president of the Florida chapter of AFP.

Florida justices are not elected to office. They are screened by a panel of legal experts, and appointed by the governor. They come up for a merit retention vote every six years, with voters asked to decide if they remain qualified for office.

Lewis and Pariente were appointed by former Gov. Lawton Chiles and Quince was appointed jointly by Chiles and former Gov. Jeb Bush. Each has been retained by voters twice before.

Merit retention was not designed to be a referendum on their controversial decisions but, for months, the justices have been bracing for such an attack — modeled after a successful 2010 campaign in Iowa. Voters there ousted three Supreme Court justices for rejecting a legal flaw in a proposal to ban gay marriage. The Iowa justices blame their defeat on last-minute television ads and campaign tactics financed by out-of-state conservative groups.

Lewis said the announcement by the RPOF shifted what had been a whisper campaign against the three justices into a frontal assault on the judiciary.

"The idea was to vote out all three justices so Gov. [Rick] Scott could replace them,’’ he said.

He urged the Hillsborough lawyers to come to the defense of the merit retention system, put in place under former Gov. Reubin Askew. He had responded to a long history of abuse and corruption in the judiciary when justices were elected to office.

"If we allow politics to overtake the three branches of government, we no longer will have the democracy we’ve enjoyed for 200 years,’’ Lewis said. "I’m trusting that somewhere in the middle there are fair-minded individuals who believe the court system is too valuable to kill through partisan politics."

The unprecedented move by the Republican Party was roundly rebuked by lawyers and former Supreme Court justices on both sides of the aisle on Monday.