Senate Majority Leader Harry Reid (D-Nev.). (MICHAEL REYNOLDS/European Pressphoto Agency) Senate Majority Leader Harry Reid (D-Nev.). (Michael Reynolds/European Pressphoto Agency)

The next showdown over the filibuster is coming, and Harry Reid and the Democrats have no choice but to take the Senate to the brink one more time.

The Senate is scheduled today to vote on the third of three nominees for the D.C. Circuit Court of Appeals; later today, Republicans are expected to defeat a cloture vote on Robert Wilkins to complete the set they began with Patricia Millett and Nina Pillard. As the Post editorialized, this is “unfair, unwise and bad for the functioning of the government.”

It also should be unsustainable. Whether Senate Democrats like the filibuster or not in the abstract (and Senate Democrats are split among groups who would like to preserve it as is, eliminate it or find some middle ground), they simply cannot allow election nullification through blocking the constitutional presidential power of nominating judges.

Democrats have been patient about imposing changes to the Senate rules by majority vote, a patience not matched by Republicans, who have obliterated the remaining norms regarding using filibusters selectively. Democrats are correct to do so, especially with judges; they remember that they were glad to have the option of blocking the George W. Bush nominees they strongly opposed and want to retain that ability for the next time that Republicans have the White House and a Senate majority. But what’s happening here is entirely different, and it calls for the strongest possible response.

Democrats have the ability to stop it. If Mitch McConnell and the Republicans don’t back down, Democrats should act. The best solution here is for Republicans to back down, allowing the filibuster to survive. But if they won’t, then Harry Reid and the Democrats really have no choice. For them to allow this to continue would be a betrayal of the millions of voters who elected them and twice put Barack Obama in the White House. Allowing nullification just isn’t an option. They’ll have to threaten to eliminate all nomination filibusters — and, if necessary, they’ll have to go through with it.