Senate Majority Leader Mitch McConnell (R-Ky.) at the Capitol in Washington on March 5. (J. Scott Applewhite/AP)

EVERY TIME the Senate majority leader has used the once-unthinkable “nuclear option,” which allows a simple majority of senators to rewrite Senate procedures over the objections of the minority, he has insisted he has a good reason. Mitch McConnell’s on Wednesday was that Democrats have wasted Senate floor time on uncontroversial presidential nominees for executive branch and judicial offices. “This is new, and it needs to stop,” Mr. McConnell said before a nuclear option vote to cut the time for which many nominees are considered on the Senate floor. “This systematic obstruction is unfair to our duly elected president.”

Mr. McConnell (R-Ky.) certainly should be able to recognize systematic obstruction when he sees it, having refined it to an art form himself. His blocking of Merrick Garland, President Barack Obama’s nominee to the Supreme Court, is the most infamous case but hardly a lonely example. As minority leader, Mr. McConnell also blockaded Mr. Obama’s nominees to the powerful U.S. Court of Appeals for the District of Columbia Circuit. That led then-Senate Majority Leader Harry M. Reid (D-Nev.) in 2013 to rashly deploy the “nuclear option” for the first time, using a Democratic Senate majority to eliminate the filibuster, and its 60-vote requirement, on all presidential judicial nominees except Supreme Court picks.

Fast-forward to President Trump’s nomination of Neil M. Gorsuch in 2017 to replace the late Antonin Scalia on the Supreme Court. With a Republican president and a GOP Senate, Mr. McConnell was the one to use the nuclear option, killing the filibuster on Supreme Court nominees by simple majority vote.

Though the Senate minority has now been denuded of its ability to block objectionable nominees, Mr. McConnell eroded minority rights further on Wednesday, using the nuclear option to end the Democrats’ use of Senate procedure to force delays on Trump nominees.

Step by step, the Senate is becoming a legislative body in which the minority party is increasingly powerless to object to presidential nominees, as long as the majority can keep enough of its members in line. Mr. McConnell’s move to strip the minority party’s ability even to delay nominees represents another step in the transformation of the Senate from one in which the rules force bipartisan compromise into one in which the majority can work its will without consulting the other party. That will lead to ever-more extreme, partisan judges and executive branch officials.

Moreover, the more often the nuclear option is used, the more it becomes a normal way of doing business in the Senate. Though senators of both parties insist they will defend the right of minority senators to filibuster legislation, a future in which the minority is less and less able to block the majority’s worst bills is also an increasing likelihood.

Sen. Mike Lee (R-Utah) stood out this week as a Republican willing to defend traditional Senate procedures. “They facilitate the compromise and accountability that are essential to the governing of a large, diverse nation,” he said. Like Mr. Reid before him, Mr. McConnell was reckless to rewrite the rules.