“He went down without a fight,” Bannon crowed. “Flake shows you one important thing: The money is getting turned off.”

GOP strategists told me that Bannon was right: The senator’s fundraising was drying up, based mostly on his dismal poll numbers. He could have run, but he would have faced a grueling yearlong ordeal that he was almost certain to lose.

And if anti-Trump Republicans can’t win their primaries, they have no place to go, thanks to the institutional barriers that protect the two-party system. In most states, including Arizona, “sore loser” laws prevent a candidate who loses a primary from trying to get on the ballot in the general election as an independent. Theoretically, Flake could have skipped the primary and tried to qualify as an independent, but that isn’t easy, either; nobody’s succeeded in doing that in Arizona since 1993.