Trump had coat tails in 2016. He gained Senate seats in 2018, and lost the House by a thin margin, despite multiple retirements by senior Congressmen. If he wins a landslide victory in 2020, it will sweep in majorities in both houses.
If the colleges stay home this fall Repubs could sweep NH. 1 Senator and 2 Reps gained, plus a few electoral votes for Trump. We allow out-of-state students to vote in-state. The liberal Dartmouth and UNH students added the few thousand votes needed to put Dems in office in 2016