Donald Trump has nominated one judge so far in his presidency, and he’s an important one: Neil Gorsuch, to the Supreme Court. But there are 117 other vacancies in federal courts across the country that Trump will have the opportunity to fill — more than twice the number of vacancies President Obama faced at this point in his first term.

“When you have the number of vacancies that you have now, that can have a big impact on the administration of justice,” said Sheldon Goldman, a political science professor at the University of Massachusetts at Amherst and an expert in judicial selection and confirmation. And if Gorsuch is an indication of the type of judges Trump will nominate, those 117 lower court vacancies will likely be filled with conservative judges, changing the makeup of the justice system for decades.

Most of the current judicial vacancies are in the district courts, but there are 18 vacancies on the Circuit Courts of Appeals, and these judges are critical in deciding the thousands of cases that do not make it to the Supreme Court. Four of those vacancies are on the 9th Circuit, the court that ruled on Thursday to uphold the order blocking Trump’s executive order on immigration.

“They are the regional Supreme Courts,” Goldman explained. “Appeals courts are the end of the line for well over 95 percent of cases.”

In total, there are 890 judge positions in the federal justice system. Nine of those are on the Supreme Court, the highest court in the country. Below that sit 11 regional Circuit Courts of Appeals, plus the D.C. and federal circuits. Each circuit is made up of the main appeals court and the lower district courts that serve as entry points to the system. Less than a month into Trump’s presidency, about one in every eight federal judge positions needs to be filled.

Trump is in the position of nominating an unprecedented number of federal judges thanks to the delay tactics by Republicans in the Senate under Obama. During Obama’s first term, only 63 percent of his circuit court nominees were confirmed, leaving 83 vacancies. The longest confirmation — for Judge Alberto Diaz, the first Hispanic to serve on the 4th Circuit — took 409 days.

Looking to quantify the difficulty presidents face in nominating judges, Goldman and his colleagues created an index to measure the level of obstruction and delay in the Senate. The index ranges from zero, which indicates the complete absence of obstruction and/or delay, to one, which indicates complete obstruction and/or delay. The 112th Congress (2011-2013) received a score of .95, making it the most obstructionist Senate ever.

In November 2013, citing “unbelievable, unprecedented obstruction,” then-Senate Majority Leader Harry Reid led the charge to change the Senate rules by eliminating the filibuster for judicial appointments, except for Supreme Court nominees. Prior to this rule change, the minority party could force the Senate to require 60 votes for confirmation. Now judicial nominees need only 51 Senate votes for confirmation.

Republicans used this rule change to their advantage when they took control of the Senate in 2015. Animosity over judicial confirmations reached its climax with the death of Supreme Court Justice Antonin Scalia in February 2016. Senate Republicans declined to give Obama’s nominee, Judge Merrick Garland, a hearing for 293 days until his nomination expired. The seat remains empty.

Without the option to filibuster, Democrats in the Senate have few methods of obstructing Trump’s nominees. They can temporarily delay hearings, but that doesn’t allow them to overcome the simple majority vote needed to confirm judges.