It raises an obvious question: Why has the Freedom Caucus, which built its reputation on promoting conservative principles through internecine conflict, quietly fallen in line behind Trump?

According to interviews with a host of Freedom Caucus members — and a National Review analysis of demographic trends and voting patterns in their congressional districts — the explanation owes both to partisan self-interest and political self-preservation.

Freedom Caucus members represent many of the darkest-red districts in America. Their average score in the Cook Partisan Voting Index is R+14, meaning a typical member’s district trended 14 points more Republican in the last two presidential elections than the country as a whole. In short, these districts are extremely conservative — and in 2016, they voted overwhelmingly for Trump.

Trump, according to the analysis, won more than two-thirds of all districts represented by Freedom Caucus members. In those he won, Trump on average carried 48 percent of the vote. And even in those he lost, Trump on average won 31 percent of the vote. This means any Freedom Caucus member opposing Trump would likely be ignoring anywhere from one-third to one-half of their district’s most engaged and reliable GOP voters.

For House conservatives, fighting against that which their constituents despised — Boehner, Obamacare, debt-ceiling hikes — always made sense, both ideologically and politically. When it comes to Trump, however, the lines have blurred: Many members harbor deep concerns about his candidacy and his commitment to conservatism, but few will raise them publicly for fear of backlash from the base.