After three years in office, President Trump has remade the federal judiciary, ensuring a conservative tilt for decades and cementing his legacy no matter the outcome of November’s election.

Trump nominees make up 1 in 4 U.S. circuit court judges. Two of his picks sit on the Supreme Court. And this past week, as the House voted to impeach the president, the Republican-led Senate confirmed an additional 13 district court judges.

In total, Trump has installed 187 judges to the federal bench.

Subscribe to the Post Most newsletter: Today’s most popular stories on The Washington Post

Trump’s mark on the judiciary is already having far-reaching effects on legislation and liberal priorities. Just last week, the 5th Circuit struck down a core provision of the Affordable Care Act. One of the two appellate judges who ruled against the landmark law was a Trump appointee.

The Supreme Court — where two of the nine justices are conservatives selected by Trump — could eventually hear that case.

The 13 circuit courts are the second most powerful in the nation, serving as a last stop for appeals on lower court rulings, unless the case is taken up by the Supreme Court. So far, Trump has appointed 50 judges to circuit court benches. Comparatively, by this point in President Obama’s first term, he had confirmed 25. At the end of his eight years, he had appointed 55 circuit judges.

Trump’s appointments have flipped three circuit courts to majority GOP-appointed judges, including the U.S. Court of Appeals for the 2nd Circuit in New York. The president has also selected younger conservatives for these lifetime appointments, ensuring his impact is felt for many years.

The executor of this aggressive push is Senate Majority Leader Mitch McConnell (R-Ky.), who is almost singularly focused on reshaping the federal judiciary, twice ramming through Senate rule changes to speed up confirmations over Democrats’ objections.

“Leave no vacancy behind” is his mantra, McConnell has stated publicly. With a 53-to-47 Senate majority, he has been able to fill openings at breakneck speed.

That philosophy did not seem to apply in 2016, when McConnell refused to allow Supreme Court nominee Merrick Garland, Obama’s choice to replace the late justice Antonin Scalia, a confirmation hearing, let alone a vote.

McConnell insisted on waiting until after the 2016 election, a gamble that paid off when Trump beat Democrat Hillary Clinton. Trump appointed conservative Justice Neil M. Gorsuch for that seat.

McConnell has repeatedly described blocking Garland as one of his greatest achievements.

Before leaving town for the holidays, Senate Republicans hailed McConnell’s success.

“You didn’t think @senate­majldr would leave town without confirming more judges, did you?” the Senate Republican Communications Center tweeted Friday, with a breakdown of the number of judges confirmed since 2017. “. . . Merry Christmas, America.”

While Trump has wavered on some conservative policies during his tenure, he has reliably appointed judges in line with conservative ideology.

“I’ve always heard, actually, that when you become President, the most — single most important thing you can do is federal judges,” Trump said at a White House event in November celebrating his “federal judicial confirmation milestones.”

The three circuit courts that have flipped to Republican majorities this year have the potential to not only change policy but also benefit Trump professionally and politically.

The 2nd Circuit, with its new right-leaning majority, will decide whether to rehear a case challenging Trump’s ability to block critics on Twitter, as well as one regarding Trump’s businesses profiting while he’s in office. The 11th Circuit, which handles appeals from Georgia, Florida and Alabama, is set to take up several voting rights cases.

Trump has facetiously thanked Obama for leaving him so many judicial vacancies.

“Now, President Obama was very nice to us. He gave us 142 empty positions. That’s never happened before,” Trump said in the Oval Office on Thursday. “But, as you know, that’s said to be the most important thing that a President has.”

When Fox News host Sean Hannity made a similar remark while interviewing McConnell on his show recently, the majority leader made clear that Obama didn’t leave those vacancies intentionally.

“I’ll tell you why. I was in charge of what we did the last two years of the Obama administration,” McConnell said, laughing.

“I will give you full credit for that, and by the way, take a bow,” Hannity responded.

In April, McConnell limited debate on Trump nominees from 30 hours to two hours, which has allowed him to push through judges at warp speed. Before that, McConnell did away with “blue slips,” which allowed senators to contest judicial nominees from their home states.

Republicans say Democrats started this trend when then-Majority Leader Harry M. Reid (D-Nev.) eliminated the filibuster for most nominees in 2013, a tool the minority party could use to block or delay a confirmation. When the Democrats lost the Senate in 2014, McConnell gained the power to stall Obama nominees, leaving Trump with plenty of vacancies.

The fast clip of judicial confirmations has no doubt shifted the courts rightward, said Russell Wheeler, a judicial branch expert at the Brookings Institution, calling it “a significant impact but not a revolutionary impact.”

At least not yet. Two-thirds of the 50 circuit court judge slots filled with Trump appointees were previously held by other Republican-appointed judges.

There is only one circuit court vacancy left for Trump to fill, but more could open up next year. And if Trump wins in November, there will certainly be vacancies in his second term. There’s also the potential for additional openings on the Supreme Court. Ruth Bader Ginsburg, appointed by President Bill Clinton in 1993, is 86 and has had health problems. Justice Stephen G. Breyer, another Clinton pick, is also over 80.

Chris Kang, chief counsel of Demand Justice, a group that supports liberal judicial nominees, wants Democrats to recognize just how high the stakes are for 2020.

“Republicans have been using the courts to achieve policy priorities that they couldn’t achieve through the democratically elected legislative branch of government,” Kang said. “These federal judges serve for life; that’s a point we take for granted, but not a way a lot of Americans understand it. Trump’s imprint on this country will be felt for decades through his courts.”

Democrats have long been reluctant to talk about the courts in a political way, Kang said. But, with Republicans choosing judges with far-right ideologies, liberals can’t “cling to romantic notions of our courts as impartial,” he added. “That’s not the reality and not how Republicans see it.”

The issue came up at last week’s Democratic presidential debate, when Sen. Amy Klobuchar (Minn.) was asked whether Trump’s appointees would make it harder for her as president to enact her agenda.

Though she didn’t answer that question directly, she said the next Democratic president will “have to immediately start putting judges on the bench to fill vacancies so that we can reverse the horrific nature of these Trump judges.”

Wheeler worries that the polarization of appointments will cause the judiciary to lose public trust, similar to what has happened with other institutions.

“We could be in for a situation if we have a rock-hard conservative majority on the Court of Appeals and the Supreme Court overturning a lot of decisions by a [future] Democratic president and Congress — you could be in for a situation where the courts’ legitimacy is called into question,” he said.

colby.itkowitz@washpost.com

Ann Marimow contributed to this report.