Brown is VERY liberal, like the 3rd most liberal senator, and his state is R+2 or so on Cook. Mandel is weak, he should seek another statewide office, or OH-16 if Renacci vacates it before running for Senate. It's clear Mandel really wants to be Senator, but he should let Kasich have this seat. Kasich would probably beat Brown by about 20 points.
Kasich very well could win by a small margin, but he wouldn't defeat an incumbent senator in a swing state by 20 points. Not happening. Also, I doubt Kasich will run for Senate anyways. I don't think many (if any) of the top Republicans will take the risk of running against Brown, so they are probably stuck with Mandel as their nominee again. I imagine many of the top Republicans in the state will probably run for the open Governors race instead of the Senate. But if 2018 ends up being a Republican wave, that could deliver Mandel a victory unfortunately...
Luckily Mandel is such a weak candidate Brown could win even in a wave. Mandel vastly underperformed all the other downticket statewide Republicans in 2014.
If Republicans were smart they'd nominate literally anybody else.
