By taking over control of the House of Representatives, Democrats may be able to block President Trump from passing any major legislation for the next few years. But by maintaining control of the Senate, Republicans can ensure that Trump will get to name a flood of judges to fill vacancies on the federal judiciary.

Senate Majority Leader Mitch McConnell already touts the remaking of the federal judiciary under Trump as one of the greatest accomplishments of the GOP-controlled Senate. Since Trump took office, the Senate has confirmed 84 judges. That includes 29 appellate court judges, as well as Supreme Court Justices Neil Gorsuch and Brett Kavanaugh.

Republicans have greatly benefited from the decision by Democrat Harry Reid, the former majority leader, to trigger the nuclear option in 2013, thus allowing federal judges to be confirmed by a simple majority vote.

Given that Trump’s hands will be tied legislatively, one of the ways in which he’ll be able to appeal to the Republican base ahead of the 2020 election will be to appoint more conservative judges.

Currently, there are 111 vacancies in U.S. District Courts and 11 vacancies on the U.S. Court of Appeals. As of now, Trump has nominations pending on 48 of those district court spots and three of the appellate slots.

Look for Trump to aggressively fill those remaining slots and for McConnell to work swiftly to confirm them. Without control of the House, the Senate won’t have the chance to enact much legislation, so McConnell can focus primarily on getting judges across the finish line. There are currently 865 judgeships at the district, appellate, and Supreme Court level. Were Trump to fill all the current vacancies on top of those he has already confirmed, nearly one out of four judges on the judiciary will have been appointed by Trump.

This, of course, does not account for the possibility of another Supreme Court vacancy opening up.

No matter what happens in 2020, the reshaping of the judiciary could end up being the most enduring part of Trump’s legacy.