I'll tell you this, though ... If I were living in Ohio there is no way in hell I'd vote against Portman just because he's calling for Trump to get out of the race. There is absolutely no upside to casting a vote for Trump while sitting on your hands and letting a Democrat win that Senate seat.
Because I'll tell you something right now: a Trump presidency and a Democratic Congress is probably the worst combination imaginable ... because you're going to find out quickly that Trump's brand of "conservative" is really nothing of the sort.