US SEN 2020: Which GOP Senate seats are the most vulnerable?

[Pragmatic Conservative]

1. Colorado (Gardner)
2. North Carolina (Tillis)
3. Georgia (Perdue)
4. Montana (Daines)
5. Alaska (Sullivan)

Maine goes to #1 if Susan Collins either resigns her seat if she runs/wins a potential governor race or retires.

[Pragmatic Conservative]

What would happen in the unlikely scenario Moore Capito retires?

Republican hold either way, West Virginia is too Republican to support a non incumbent Democrat in a Senate race.

[Pragmatic Conservative]

What would happen in the unlikely scenario Moore Capito retires?

Republican hold either way, West Virginia is too Republican to support a non incumbent Democrat in a Senate race.

What about Jim Justice? WV voted for a non-incumbent Democratic governor in 2016, where Trump won every county. Do you think incumbent Joe Manchin loses in 2018?

Manchin will probably win re-election but that is largely because he is personally popular (though certainly not safe). Governor and state elections are fairly disconnected from state elections, so you can have a Democratic governor like Justice in West Virginia and a Republican governor like Hogan in Maryland.