WASHINGTON — In a historic move, Democrats in the Senate today eliminated the use of the filibuster as a tool to block presidential appointments, upending a decades-old precedent that gave the minority party unique leverage on nominations.

After threatening to change the rules several times this year, the Democratic majority pulled the trigger on the so-called nuclear option after a series of procedural maneuvers that played out before a packed chamber. It would allow a president’s nominees, except for seats on the Supreme Court, to be confirmed by a simple majority, rather than the 60-vote threshold that had become the norm.

Fifty-two senators voted in favor of the changes, with 48 voting in opposition.

Just three Democrats, Sens. Mark Pryor of Arkansas, Joe Manchin III of West Virginia, and Carl Levin of Michigan, opposed the move.

President Obama said he supported the vote.

Senate Majority Leader Harry Reid, D-Nev., argued that the change was needed in the face of unprecedented Republican obstruction of nominees, which prevented the president from fulfilling his constitutional duty to fill vacancies in the courts, as well as in his administration.

More broadly, he argued that the Senate threatened to become “obsolete” if it did not act to end gridlock.