All 8 races look very difficult to me; kind of like climbing Mt. Sinai if not Mt. Everest.
Jeff Bell may be Mt. Everest but he deserves our full support. Mike McFadden in Minnesota may be Mt. Sinai but he has the cash to wage a war. I did not include Tillis of North Carolina whose opponent deserves defeat but whose own bona fides are somewhat in question. Landrieu is beatable. Alaska and Michigan are also quite winnable.
Don't be a pessimist.