Updated

Editor's note: The following column first appeared in The Washington Post.

The allegations by five women that Roy Moore pursued and sexually molested teenage girls while he was in his 30s are disgusting, and disqualify him to serve in the United States Senate. Conservatives should be outraged at Moore for his loathsome conduct. But they should also be outraged at the man who helped put Moore on the ballot and is in the process of destroying the Trump presidency: Stephen K. Bannon.

If the man Trump supported in the primary, Sen. Luther Strange, were the Republican nominee today, the GOP would be cruising to an easy victory in the Dec. 12 special election. But thanks to Bannon’s insurgent campaign for Moore, Republicans could lose the Alabama Senate seat.

This should be unthinkable. Alabama is one of the most reliably Republican states in the union. No Democrat has gotten more than 40 percent of the vote in a Senate race there since 1996, and every Republican since has won by a margin of between 18 and 35 points. But a new JMC Analytics poll has Moore trailing Democratic opponent Doug Jones by four points, while a Decision Desk HQ/Opinion Savvy poll shows the race tied, 46 percent to 46 percent. An Emerson College poll shows Moore still ahead by 10 points, but even there his lead has been cut by more than half since the allegations surfaced. The Cook Political Report has moved the race from a safe Republican seat to a “toss up.”

A growing number of Republicans say they won’t vote for either candidate. And if more credible allegations emerge before Election Day, Moore’s remaining support could crumble. One poll(which has Moore up by just four points) found that 37 percent of voters say Moore should withdraw, but that number goes up to 64 percent “if the allegations are true.” This suggests that many Alabama Republicans don’t believe the accusations. But if more voters are persuaded as more evidence emerges, it could give Democrats the margin of victory.

Win or lose, Moore’s candidacy is a disaster for the GOP. If he wins despite the allegations, it will send a signal to women everywhere that Republicans do not believe that credible allegations of a grown man molesting a 14-year-old girl are disqualifying. And if he loses, his defeat will dramatically increase the chances that Democrats will win control of the Senate in next year’s midterm elections. That means no more conservative judges, no more conservative legislation — effectively ending the Trump presidency. Democrats would also be in charge of the Russia investigation and have unbridled subpoena power. And if Democrats also win control of the House, then it’s impeachment time. If any of that comes to pass, Trump can thank one man: Bannon

Even if Republicans manage to hold the Senate, Bannon’s campaign to unseat GOP incumbents is making it less likely that Republicans will expand their Senate majority in 2018. It should be clear by now that having 52 GOP senators is not enough to pass Trump’s agenda. So conservatives should be pouring all their resources into defeating vulnerable Democrats, not diverting millions from those efforts to fund Bannon’s needless internecine war.

Now that Bannon is doubling down in supporting Moore, Republican donors must stop supporting Bannon’s war against Republican incumbents. They should follow the lead of Sheldon Adelson, who this week announced a break with Bannon. And Trump should intervene to stop Bannon’s continued support of Moore and publicly urge the members of Alabama’s Republican Party central steering committee to pull Moore’s nomination when they meet later this week.

Competitive primaries can be a good thing. That is how Republicans ended up with some of their best conservative senators, including Patrick J. Toomey (Pa.), Marco Rubio (Fla.) and Mike Lee (Utah). But in this case, they ended up with an alleged predator. Goodness knows he would not be the first one to walk the halls of the Senate. I was a Senate staffer when the Packwood Diaries were released, which detailed then-Oregon Sen. Bob Packwood’s sordid history of advances on women. He resigned under threat of expulsion. But those details emerged after Packwood was elected. In this case, Alabama voters would be sending Moore to Washington with full knowledge of the allegations against him.

That puts Republicans in a quandary. For all the grand talk of expelling Moore after he is elected, it is an open question whether Republicans would really set the precedent of kicking out a senator for alleged behavior — no matter how heinous — that happened decades before he was elected to the Senate, particularly if it was known to the voters who elected him. Moreover, expulsion is not so simple. Moore would be seated, and there would be an ethics investigation that could take months — with public hearings and witnesses. That is a spectacle no one wants.

The best solution is to make sure Moore never makes it to Washington. Some have suggested that Attorney General Jeff Sessions launch a write-in campaign, but this could split the GOP vote and thus make a Democratic victory more likely. So Republicans, including the president, had better act quickly and get Moore to step aside.