Why aren’t more Republican senators opposed to Pete Hegseth’s nomination as secretary of defense, particularly in light of new allegations, delivered in a sworn affidavit this week by his former sister-in-law, of excessive drinking and “abusive” behavior in his second marriage ?

The obvious answer is party loyalty. In 1989, President George H.W. Bush picked John Tower, a former Republican senator from Texas, to serve as secretary of defense. Like Hegseth, he was a military veteran who had been dogged by charges of womanizing and heavy drinking. Unlike Hegseth, he had top-level experience in defense matters, including the chairmanship of the Senate Armed Services Committee.

A history of heavy drinking should be disqualifying in nearly any leadership role, never mind one with responsibilities as vast and consequential as the Pentagon’s. Even so, only one Republican senator — Kansas’s Nancy Kassebaum — voted against Tower, who went down in defeat, 47 to 53. If Hegseth’s candidacy, which could come to a vote as early as Friday, is opposed by any Republican, it will most likely be from another independent-minded woman, Maine’s Susan Collins.

(Through his lawyer, Hegseth has denied his former sister-in-law’s claims, and denied as well that he has issues with alcohol. In a statement to NBC News, his ex-wife said, “There was no physical abuse in my marriage.”)

In the case of Hegseth, the power of party loyalty is compounded by three additional factors: fear of Trump, the Cult of MAGA and the boomerang effect of liberal scorn.

As to the first: At least Kassebaum didn’t have to fear a social-media fusillade from Bush, and Bush would have been too much of a gentleman to do more than fume in private over her vote. Today, any Republican senator who defies Trump risks not just public mockery and belittlement from the president, but threats of a primary challenge, too.