Yes... he should make a campaign stop in the District once he sews-up the nomination.
Trump doesn’t need to endorse Nehlen. All Nehlen needs to do is run on a pro Trump platform, and do so now. In doing so he will get great media coverage and beat Ryan to the punch. It will then be game over for Ryan.
Ryan got rolled by super genius, one Patty Murray, demoCRat... He’s weak sauce! Boot him in da primary!