Democrats are trying to resurrect their unprecedented filibuster of judicial nominees through the blue slip tradition, but Senate Judiciary Committee Chairman Chuck Grassley (R-IA) has the power to stop this obstruction.

Filibustering is when senators continue debating a measure as a stalling tactic to prevent it from coming to a final vote, often because they know the measure would pass. Under Senate rules, for any “debatable question”—which for most of the Senate’s history was thought to mean legislation—any senator can keep debate going until the Senate invokes cloture to limit debate.

A cloture motion requires three-fifths approval, which means 60 senators in the 100-member Senate. If 41 senators stick together to vote against cloture, debate on the matter before the Senate can continue indefinitely, preventing an up-or-down vote.

The first partisan filibuster of a judicial nominee occurred in 2003, when Senate Democrats blocked several of President George W. Bush’s picks for the federal appeals courts. Previously, the filibuster had on rare occasions been used to block nominees that had bipartisan opposition and would have been voted down if brought to the Senate floor for a final vote, with President Lyndon Johnson’s nomination in 1968 of Abe Fortas for chief justice being the clearest example. But in over 200 years of American history, a partisan group of senators in the minority had never blocked a nominee that a majority of senators was ready to confirm.

When Republicans decided in 2013 to try this same tactic on a select few of President Barack Obama’s nominees, Senate Democrats voted to reinterpret Senate rules to abolish the filibuster for all federal courts below the Supreme Court. They also invoked this “nuclear option” to abolish the filibuster for all executive branch nominees.

But in 2017 roles were reversed, with a Republican in the White House and Republican control of the Senate, meaning that Democrats lacked the numbers to defeat judicial nominees unless the opposition were bipartisan. Senate Democrats decided to take their tactic to its ultimate conclusion, by attempting to filibuster the nomination of Neil Gorsuch to the Supreme Court.

Gorsuch was so supremely well-qualified for the High Court that it became clear that Senate Democrats would filibuster any Supreme Court nominee that President Trump would put forward. Senate Republicans therefore invoked the nuclear option, extending the Democrats’ procedural rule to cover the Supreme Court in the same manner that it covers every other court. Justice Gorsuch was confirmed.

But Senate Democrats are not returning to a collegial working dynamic on judges. Instead, they are claiming additional rights under the blue slip process.

As a matter of senatorial courtesy, when the president nominates a person for a federal judgeship, the chairman of the Senate Judiciary Committee will send a paper form called a blue slip to that nominee’s two home state senators, asking if those senators approve of the Judiciary Committee considering the nominee. The blue slip is offered as a courtesy, and typically those blue slips are promptly returned, informing the chairman that regardless of whether that senator will ultimately vote to confirm the nominee, the senator consents to the committee’s moving forward on the nomination.

Until now.

Three of President Trump’s nominees to the federal courts of appeals are from states with one or two Democratic senators. Joan Larsen is a justice on the Michigan Supreme Court and a former law clerk to Justice Antonin Scalia, and has been nominated to a seat on the U.S. Court of Appeals for the Sixth Circuit. Allison Eid is a justice on the Colorado Supreme Court and a former law clerk to Justice Clarence Thomas, and has been nominated to the Tenth Circuit. And David Stras is a justice on the Minnesota Supreme Court and also a former law clerk to Justice Thomas, and has been nominated to the Eighth Circuit.

The five Democratic senators from those states—Michigan’s Debbie Stabenow and Gary Peters, Colorado’s Michael Bennet, and Minnesota’s Al Franken and Amy Klobuchar—have all refused to return on the blue slips on their home-state nominees.

However, blue slips are only a tradition; they are not required by federal law or by Senate rules. Chairman Grassley therefore has the option to decide that he will move forward on a nomination regardless of whether he received two blue slips from the home-state senators.

No one has alleged any concerns or problems with the qualifications of Larsen, Eid, or Stras. It is clear that the blue slips have not been returned solely because those senators do not want those judicial nominees to receive a final vote. This is the same kind of obstruction that was used against Justice Gorsuch. Any senator who will not support these appellate nominees would not support any Trump nominees.

Blue slips are thus being used to resurrect filibustering judicial nominees, except that instead of 41 senators, it takes only one.

But the solution is also about one senator. Just as Chairman Grassley voted as a member of the full Senate to end the judicial filibuster, he can also decide now that as committee chairman he will discontinue a tradition that started as a courtesy to colleagues, but has now become a tactic of uncompromising and unprecedented obstruction.

It is imperative that the many vacancies on the federal courts be filled. Chairman Grassley’s discontinuing the blue slip tradition may be the only way to confirm well-qualified nominees to the federal bench.

Ken Klukowski is senior legal editor for Breitbart News. Follow him on Twitter @kenklukowski.