After voting to change the rules Thursday, Democratic senators advanced the nomination of Patricia Millett to serve on the D.C. Circuit Court.

Republicans had blocked her nomination earlier this year — as well as two other nominees to the second most important court. That prompted Senate Majority Leader Harry ReidHarry Mason ReidGOP moves to cut debate time for Trump nominees Harry Reid: ‘The less we talk about impeachment, the better off we are’ Lobbying world MORE (D-Nev.) to use the “nuclear option” to change the Senate rules with a simple majority Thursday.

The Senate voted 55-43 to end debate on Millett's nomination — 60 votes were required before the rule change.

Republicans had blocked up-or-down votes on three of Obama’s nominees to the D.C. Circuit Court — Robert Wilkins, Cornelia Pillard and Millett. And Caitlin Halligan withdrew her nomination because of GOP threats to block her confirmation.

GOP senators argued it wasn’t because of the nominees' character or qualifications, but because the D.C. Circuit caseload was so low that the three vacancies don't need to be filled.

Reid said Republican obstruction had gone too far.

The nuclear option — which gets its name from the damage done to bipartisan relationships — allows a simple-majority vote to change the Senate rules rather than a usual supermajority.

The damage to bipartisanship was already evident in the fact that Sens. Lisa Murkowksi (R-Alaska) and Susan Collins (R-Maine) voted against Millet's nomination this time. In previous cloture votes they had supported her nomination, but their two votes weren't enough to help Democrats overcome the 60-vote threshold.

Reid had threatened to use the nuclear option several times this year. But each time lawmakers have gathered to discuss alternatives. At the beginning of the year Republicans vowed not to filibuster any of President Obama’s nominees unless there were “extraordinary circumstances.” Democrats say the GOP has reneged on that promise.