I wonder if Trump gets elected but the democrats sweep the congress, I wonder if they'll turn the SC filibuster around and start blocking everyone trump proposes.
They probably won't sweep the house due to gerrymandering, but there's a chance that they'll get a slim minority in the senate. At least until 2018 when there are about the same number of democrat seats up for election as there are republican seats up for election this year.
And the democrats turning the SC filibuster around isn't an if, it's a definite certianity. However, Trump isn't exactly popular among the republican establishment and so, the democrats may find some allies among the republicans, but who knows. Although stuff I've read have said that the republicans will just return to their old partisan ways when Trump gets elected, but again, this year is so unusual that maybe they won't, maybe they'll fracture due to infighting.
Has a cross-candidate sweep ever even happened? The Dems don't just need a couple seats, they need quite a few.
What do you mean by cross-candidate sweep?
Going by the new Senate numbers on 538, Dems have about a 50% chance of having 51 seats in the Senate which is the only part of congress that matters for nominations. But the democrats are almost certain to lose a lot of Senate seats in 2018.
Not neccesarily, two years is plenty of time for Trump to royally screw up. Doesn't change the fact that there are as many dem seats up for election/re-election as there are rep seats up this year.
Still, even if they don't get a majority, they'll definetly try to make things as difficult as possible for Trump. Though they'll have to try not to stoop to the levels the republicans have gone.