Will Trump support the (hypothetical) primary oppnts. of internal party critics?

[🦀🎂🦀🎂]

This would be largely unprecedented (since FDR?) but, heh, Trump is a pretty unprecedented guy. Would Trump try and oust his Republican enemies if they scupper his plans? In particular, Flake, Ryan, Cruz, Amash, Roby, Wagner might targets based on their actions in 2016.

[GlobeSoc]

This is actually a potential factor in,or could cause on its own, a Democratic wave. 

[Heisenberg]

A lot has to do with how the particular politicians are, and whether or not the're friendly with the establishment. I'll go one by one:
Flake: If Kelli Ward ends up being the only primary challenger, he has nothing to worry about. I also think Flake is favored in the general if he wins his primary, but it will be targeted, and he can still go down.
Ryan: No. Trump is not going to publicly oppose the Speaker's reelection while in office.
Cruz: Can't see a credible primary challenge materializing, and the last thing Republicans would want is a costly battle in Texas, and potentially defending the seat there. The likely Democratic candidate, Beto O'Rourke, is way too far left to win statewide, and is from the wrong part of the state.
Amash: He is one I can realistically see the establishment targeting (he's Freedom Caucus and Tea Party affiliated, and breaks from the GOP on some foreign policy issues, like Israel). In Michigan, due to short term limits, there's a good bench of potential primary challengers, and someone with a more populist streak could unite the Trump and Ryan factions. In the off-chance he goes for the Senate seat, then Trump (and the establishment) are almost certain to back someone else. Amash is a bad fit for the state, he won't win since he'd get crushed in Oakland and Macomb counties as he has no blue-collar populist appeal. Dan Benishek would be the best Republican, but I don't think he can beat Stabenow.
Roby: She got a primary challenge this year against a some dude(tte), but after unendorsing Trump, many angry Republicans wrote in the primary challenger, keeping Roby's win within 10 points. Talk is that the primary challenger may run again next year, and if she does I think Roby can go down.
Wagner: She seems to be preparing for a Senate run. But, given Missouri's history of competitive Republican primaries, I expect someone else to run against her. Rep. Sam Graves is a possibility, since Eric Greitens named his brother Todd Graves the chair of the Missouri Republican Party. Given that, Greitens would likely back Graves, and I can easily see Trump doing so as well.

Case in point, Trump is most likely to oppose the last three (Amash, Roby, and Wagner).

[Santander]

Flake is a possibility. No way Trump goes after Ryan or Cruz. I don't see Trump getting in the mud over one or two House seats that the country as a whole don't care about.