I think Manchin would win rather easily. Justice is unpopular, and Republican voters would rather have the Senate seat than the Governorship, methinks.
You think that Republican voters of WV (and other states, for the record, I am not just spitting upon rural America from my ivory private liberal arts college tower for once) are smart enough to think of how Manchin's governorship would benefit Republicans? They'll just see (R) and vote Justice cause he's not an evil Demoncrat. If Manchin does run and does win, it'll be by about the same margin his Senate race was, maybe less.
Also, lmao at this:
put in a successor who's likely to hold the seat not just in 2024 but in several elections to come, and continue working at the state level to build the party.
