President Trump thinks the Gorsuch appointment to the Supreme Court is one of his biggest achievements of his presidency. Another major success may await him: the redirection of the lower federal courts, such that there will be more Republican than Democratic appointees, and thus a more conservative federal judiciary.

Democrats know the judicial map, yet what can they do to slow the Republicans down? It takes just 51 votes to confirm a judge, and there are 52 Republicans.* The Democrats are in the minority, and they no longer have the filibuster, a tool that they themselves did away with when they were in the majority in 2013. Trump and Senate Republicans would appear to be able to have their way in picking judges unless Democrats take the Senate in 2018, which most election analysts consider unlikely.

The week after the 2016 elections, Russell Wheeler of the Brookings Institution explained the opportunity for Trump. The majority of judges taking senior status or retiring during Trump’s term will be Republican appointees, said Wheeler. Trump appointees thus will likely replace more Republican appointees than Democratic ones, but the president may still be able to create by 2020 modest Republican-appointee majorities among judges in full-time status.

Trump inherited 96 vacancies on the district courts, a number Wheeler thinks will grow to 150 during his term, 110 of which will be filled by mid-summer of 2020, as judicial selection usually shuts down then in the runup to the presidential election.

If Wheeler is right, Republican appointees to the district courts will number 339, 107 more than they did on Jan. 20, 2017, while Democratic appointees will number 292, 53 fewer than they did at the start of 2017. Some 138 seats will be vacant—96 of them created by exiting Democratic appointees.

The more important lower courts are the appeals courts, which decide almost all cases, the Supreme Court taking only a very few for review. On Inauguration Day, Republican appointees numbered 72 and Democratic ones 91, and 16 seats were vacant. Wheeler thinks the numbers by mid-2020 could be 94 and 77, respectively, with 8 seats vacant.

In January 2017 Democratic appointees had majorities on nine courts of appeals, and supermajorities—meaning twice as many or more—on five. Republican appointees had supermajorities on four. If Trump replaces all 48 of the Democratic appointees that are positioned to leave office and do so during Trump’s term, said Wheeler, “every court of appeals would become a Republican-appointee majority court.” That’s highly unlikely, in Wheeler estimation, but he is right to think that “some closely divided courts seem poised to shift from Democratic-appointee majorities to Republican appointee majorities and from narrow Republican majorities to more robust such majorities.”

The Senate has confirmed three judges for the courts of appeals, and one for the district courts.About 30 nominees—eight for the courts of appeals and 22 for the district courts—are awaiting Senate action. There are now almost 140 open seats, 28 more than Trump inherited.

Minority Democrats in the Senate aim to slow the confirmation process by practices that the majority Republicans should be able to control. The weight given to a senator’s objection to a nominee from the senator’s home-state is an issue—one that the chairman of the Judiciary Committee, Republican Charles Grassley, can decide. And there is the matter of the number of hours a nomination may be debated on the floor—it’s now the absurdly large amount of 30 hours, and Republican Senator James Lankford has proposed cutting it back to 8 hours, at the end of which there would be an up or down vote.

What is ultimately at stake is the philosophical direction of the federal judiciary—whether, in broad terms, we select judges, and justices—who interpret the law or make it up. Someday we could be discussing Trump judges, just as we do now Reagan judges.

*Correction: This post initially said that there were 54 Republican senators.