Ginsburg & Breyer were warned to let Democrat replace them.

Harvard Law School professor Randall Kennedy shocked the legal world in 2011 when he called for the immediate retirement of two members of the US Supreme Court’s liberal wing: Ruth Bader Ginsburg and Stephen Breyer.

Saying it was the “responsible thing for them to do”, Kennedy argued in an essay for The New Republic that the septuagenarians — who were both nominated by Bill Clinton — should step aside so then Democratic president Barack Obama could name younger liberals to replace them to lifetime seats on the nation’s highest court.

Neither heeded the call. Last year, Ginsburg died aged 87 and her seat was filled by Donald Trump just days before the November presidential election with Amy Coney Barrett, tipping the balance of the nine-member bench 6-3 in favor of conservatives.

Now, with Democrats in the White House and controlling the Senate by the slimmest of margins, Breyer, 82, is facing fresh demands to step down after nearly 27 years on the court.

As the Supreme Court nears the end of its term, he has been targeted by a fierce public pressure campaign that presents political challenges for President Joe Biden as progressives fret about a conservative-dominated Supreme Court ruling on everything from voting rights and guns to affirmative action and abortion.

“We have seen the tragic consequences of rolling the dice, and that simply cannot be allowed to happen again,” said Tré Easton of the progressive group Battle Born Collective. “The GOP does not pretend that the court is this apolitical institution, and the left, progressives, Democrats, can’t afford to pretend that it is apolitical either.”

"Justice Breyer may conclude that it is more damaging to the court as an institution for him to yield to this type of campaign than for him to remain on the court," said Jonathan Turley, George Washington University Law School

Those calls grew louder after Mitch McConnell, the top Senate Republican, recently suggested he would stand in the way of a Biden nominee if the GOP seizes control of the upper chamber in next year’s midterms.

Supreme Court justices are selected by presidents but require confirmation by a simple majority in the Senate.

McConnell famously refused to take up Obama’s nomination of Merrick Garland to fill the vacancy created by the death of conservative Antonin Scalia in 2016, setting the stage for Trump to pick Neil Gorsuch instead.

McConnell’s latest comments sparked outrage among progressives. “Anyone who still doubted that Stephen Breyer not retiring could end in disaster should pay attention to Mitch McConnell,” said Brian Fallon, executive director of left-leaning group Demand Justice.

Fallon’s group has led a “Breyer Retire” campaign, launching an advert campaign and hiring a billboard truck to circle the court building with the message: “Breyer, retire. It’s time for a black woman Supreme Court justice. There’s no time to waste.”

Some legal scholars have joined in, including University of California at Berkeley School of Law dean Erwin Chemerinsky, who wrote in a Washington Post op-ed last month that Breyer should “learn from Justice Ginsburg’s mistake” and step down now, warning: “With a 50-50 Senate, anything is possible”.

Biden has vowed to appoint the first black woman to the court should a vacancy arise. Ketanji Brown Jackson, widely seen as one of the frontrunners, was confirmed earlier this week by the Senate to serve on the prominent federal appeals court in Washington DC.

A Breyer retirement could be one of Biden’s only opportunities to appoint a Supreme Court justice in the near future, barring any unexpected developments.

Clarence Thomas, an avowed conservative appointed in 1991, is the second-oldest on the bench — and 10 years Breyer’s junior.

Trump had the rare opportunity to fill three vacancies in his four-year term, following the deaths of Scalia and Ginsburg and Anthony Kennedy’s retirement.

Like many Republican lawmakers, he campaigned on the promise of a conservative court to woo Republican grassroots voters who feel strongly on issues such as guns and abortion.

Biden, meanwhile, has largely avoided wading directly into issues relating to the court, though earlier this year he set up a bipartisan commission to consider reforms, including adding more Supreme Court justices.

Asked in April about the president’s view on calls for Breyer to step down, Jen Psaki, White House press secretary, said it was the justice’s decision to make. This week, Biden said of McConnell’s veiled threat: “Mitch has been nothing but ‘no’ for a long time, and I am sure he means exactly what he says. But we’ll see.”

Supreme Court justices are typically tight-lipped, rarely giving interviews or commenting on issues. Breyer, a Harvard Law School graduate and former professor whose CV includes stints at the US justice department and the 1st US Circuit Court of Appeals, has said little about his plans.

He made headlines earlier this year when he gave a lecture at Harvard titled “The Authority of the Court and the Peril of Politics”, in which he rejected calls to “pack” the court with additional justices, and defended the institution’s independence from the White House and Congress.

“If the public sees judges as politicians in robes, its confidence in the courts — and in the rule of law itself — can only diminish, diminishing the court’s power, including its power to act as a check on other branches,” Breyer said.

Jonathan Turley, a professor at the George Washington University Law School, said the speech suggested Breyer might not take kindly to the political campaign calling for his departure.

“There is no question about Breyer’s continued intellectual acumen or abilities, so the question is whether he feels he needs to leave the court,” Turley said. “Justice Breyer may conclude that it is more damaging to the court as an institution for him to yield to this type of campaign than for him to remain on the court.”