It depends in part on whether or not the Republicans have decided, after all, that the strong horse is Trump. If the R party goes back to obstruction and opposition then the elections will be iffy.
I think the Republicans will hold back enough to lose the senate so the impeachment proceedings can begin while the Republicans wring their hands and tell us they tried... but they just don’t have the votes.
We will see... most seem to be RINO, and/or “go with the flow”..
Hopefully, Trump at least set them in the right direction.