Roy Moore’s defeat shows that Steve Bannon is for losers.

Alabama voters can be forgiven if they preferred to sit out Tuesday’s special Senate election, but those who turned out narrowly elected Democrat Doug Jones to fill the seat vacated by Attorney General Jeff Sessions. The result is a painful lesson for the Alabama Republicans who nominated Roy Moore in the September primary. But it’s also a useful act of political hygiene for the national Republican Party given the accusations of sexual misconduct against the former judge. The cost of defeat will be high and immediate. Despite his campaign vows to “cross the aisle” to work with Republicans, Mr. Jones will fit right in with Senate Democrats. He will be a reliable vote for Chuck Schumer on any important matter, including judicial nominees. Had he shown even a scintilla of moderation on abortion, for example, he would have won in a rout. Mr. Moore’s defeat narrows the GOP majority’s margin to 51-49, which will give even more leverage to individual Senators who want to grandstand or satisfy a political constituency. Alabama evangelical Christians who supported Mr. Moore over appointed Sen. Luther Strange in the GOP primary should know that they have now made a conservative Supreme Court nominee less likely if Justice Anthony Kennedy retires in 2018. Senators Lisa Murkowski and Susan Collins will hold the balance of judicial confirmation power, and watch the media lobby them in waves. The good news is that Mr. Moore’s loss may give the GOP a better chance of holding the Senate majority next year. Democrats were primed to make Mr. Moore a national symbol of sexual harassment to drive turnout among women. GOP incumbents would have been asked about Mr. Moore every day. As for Alabama Republicans, they’ll get another shot at Mr. Jones in 2020. Maybe they’ll learn from this debacle and nominate a candidate worthy of support.

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