Democrats actually have a chance in the House. Every seat in the House is up for election in 2018, and we’ve already seen from special elections in very red districts in Kansas and Georgia that even very red districts are vulnerable. Furthmore, a recent Quinnipiac poll says that 38% of America wants to see Congress controlled by Republicans and 54% wants to see Congress controlled by Democrats. While polls of this sort aren’t often accurate predictors (everybody wants to throw the scumbags out, but not THEIR scumbag), this is the biggest differential we’ve seen for some time, and Republicans should be concerned.
The Senate? Not so much this time around. Of the 33 seats up for election in 2018, only eight are held by Republicans. Two are held by independents who caucus with the Democrats, and the other 23 are all held by Democrats. Even if all eight of the GOP seats flip blue and all the Dem/Ind seats stay blue, that will turn the Senate to Dem control, but not enough for a supermajority. Trump has to lose the support of the Republicans much in the way Nixon did in 1974.