So, the Senate should stay Democrat? Is that what you're saying?
Now, if we're talking about singular races, fine. There are good individuals out there and some races are worth supporting. However, supporting “Republicans” because they are some kind of firewall is naive and is part of the Punch and Judy show we've been trained to play. The real polarity is anarchy or dictatorship and pubbies have been just as comfortable with maintaining power as the Marxists, er, Democrats for decades.
IMO, being on the cusp of great change also allows for chaos in planned transition. Our final options might include formation of another party, candidates that are independent or . . . who knows. The point is that the D/R, right vs. left continuum is patently bunk and has done little to nothing to change or arrest our slide (”slouching” as Bork put it) toward destruction.
There is no rescue in politics - only compromise. Revolution is what we're facing and it may, or may not, go as planned. Either way, too much of the GOP is invested in keeping the status quo to be our salvation.
Personally, I don't believe in salvation from the hand of man so, for me, this question takes a back seat to more important choices in the home, family and social spheres because our binding culture is dead. Renewal begins at home.
Just my $0.02.