In January, it was Roberts facing scrutiny about how he’d run Trump’s impeachment trial — an inherently political proceeding.

And almost every time, the flare-ups inevitably have led to calls for the justices to recuse themselves from any Trump-related manner.

That presents a perilous challenge for Roberts, who since becoming the country’s top jurist 15 years ago has striven to keep the court above politics. But each new incident only underscores the obstacles ahead as the Supreme Court takes up a series of explosive election-year cases on abortion, immigration and presidential power that put it at the center of the political fray.

“It’s a sad reflection of the politicization of the Supreme Court,” said Philip Lacovara, a former deputy solicitor general and lead counsel to the Watergate special prosecutor.

The court’s election-year docket has several cases in which the new conservative majority could flex its muscles.

Last Wednesday, the Supreme Court heard arguments in a case examining Louisiana’s abortion restrictions, the case that led Roberts to publicly rebuke Schumer for a comment that the two Trump-appointed justices would “pay the price” if they ruled the way the Trump administration prefers.

And at the end of March, the court will consider whether Congress can subpoena the president’s personal records and whether Trump is immune from state criminal investigations while serving in the White House.

The justices will also render an opinion in the coming months on Trump’s efforts to phase out an Obama-era program shielding 700,000 undocumented immigrants from deportation, and will eventually consider whether to dive into questions connected to the Affordable Care Act and sanctuary cities.

But at the rate Trump and some of his critics are calling for justices to recuse themselves, there would be only a couple of justices left to hear these cases.

The recusal calls are hardly academic.

For starters, Roberts faced questions about whether he’d need to recuse himself from matters involving the president because of his unique role as presiding officer during the Senate impeachment trial. Some Republicans warned that he had to be careful about stepping into the mix, given his upcoming role in several Trump-related cases.

“He will have to hear executive privilege cases at some point in his term. If he rules on those now, he’ll have to recuse himself in future cases, and that’s a terrible idea,” Missouri GOP Sen. Josh Hawley told reporters in the Capitol in January during the impeachment trial.

Then, of course, there’s Trump. The president inserted himself into the debate last month, making a highly unusual call for Ginsburg and Sotomayor to pull themselves from cases involving him or his administration because he claimed they’d both displayed anti-Trump bias.

“She’s trying to shame people with perhaps a different view into voting her way, and that’s so inappropriate,” the president said of Sotomayor, the Barack Obama appointee who in a recent dissenting opinion fretted that her conservative colleagues were disproportionately granting stay requests from the current administration over other emergency applicants.

The liberal group Take Back the Court countered by pressing for Thomas, a George H.W. Bush appointee, to drop off any cases involving the president because of his wife’s close ties to the Trump White House. That’s on top of its calls last fall for Brett Kavanaugh and Samuel Alito to recuse themselves from a case on LGBT rights after the two conservative justices posed for a picture in a Supreme Court conference room with the head of the National Organization for Marriage, a non-profit that has lodged arguments before the justices opposing gay marriage.

“Trump seems to think justices should recuse if they aren't loyal to him,” said Aaron Belkin, executive director of Take Back the Court. “We think they should recuse if they're creating the reality or appearance of improper influence — and the very loyalty Trump demands would itself be grounds for recusal.”

Calling for Supreme Court justices to recuse themselves isn’t a new phenomenon.

While there are no formal rules on the matter, the court’s lifetime members will often back out of a case when it touches on a personal relationship, or if they’ve outed themselves by showing bias in one direction or another. Supreme Court watchers also say there’s an unwritten rule that discourages justices from recusals where their absence could result in a 4-4 tie.

Former Chief Justice William Rehnquist didn’t participate in the seminal Richard Nixon Watergate tapes case because he’d served in the Nixon Justice Department. Antonin Scalia sat out a 2004 case that preserved the phrase “one nation, under God” in the Pledge of Allegiance after making previous remarks that appeared to show he already thought the language was constitutional.

In her first few months on the job, Justice Elena Kagan had to sit out at least 20 cases because of her work as the Obama administration’s solicitor general.

But Scalia rejected calls from environmentalists to sit out a 2004 case because of a hunting trip he’d taken with Vice President Dick Cheney, explaining in a detailed 21-page memorandum , “If it is reasonable to think that a Supreme Court Justice can be bought so cheap, the Nation is in deeper trouble than I had imagined.”

Legal scholars said the more recent recusal discussions are not nearly as serious.

Thomas’ wife, for instance, isn’t governed by any judicial codes, said Stephen Gillers, a New York University law professor.

“It might be that her activities would require recusal of Thomas in a particular case in which they figured, but her views on a political issue are not attributed to her husband if the same issue reappears as a legal question in a Supreme Court case,” Gillers said.

As for Sotomayor, she was “simply the justice doing her job,” he added. “Her perceptions may be right or wrong, but they are not a basis for recusal. Writing opinions on the law and procedure is what judges and justices do.”

Ginsburg has been dinged for her 2016 criticism of Trump, then an insurgent GOP presidential candidate. The remarks, Gillers said, might force her recusal in a situation like Bush v. Gore, the 2000 Supreme Court decision that ended a Florida recount and effectively handed the election to George W. Bush. But beyond that, “nothing she said requires recusal from all Trump cases.”

And with Trump, his recusal calls were seen as mere political posturing, as is often the case.

“It is telling that despite Trump’s comments, government lawyers have not sought recusal of either justice,” Gillers said.

“I think this is the president’s genius at being able to control the conversation and rile up his supporters, at work,” said Tom Goldstein, co-founder and publisher of SCOTUSblog. “His arguments for recusal are stupid. But it doesn’t matter. They get covered, and validated as a result as if they represented a legitimate view of the law. His supporters pile on. And in the meantime, serious discussion of other topics gets derailed.”

Even Alan Dershowitz, the retired Harvard law professor and frequent Trump defender, said he’d caution against the president asking for a recusal of someone like Roberts for his role in impeachment.

“I don’t think it’d be in his interest to do it. If I were on the legal team, which I’m not, I’d not make the recommendation,” he told POLITICO in late December, a few weeks before the president tapped him to make arguments in his defense on the Senate floor during the impeachment trial.

Dershowitz had another reason to advise against taking aim at the Supreme Court — especially for someone with business before the justices.

“Making motions for recusal is like throwing a stink bomb,” he said. “If it’s denied, you put yourself at a significant disadvantage.”