The Republicans want war by default, it’s required to keep the American economy ticking over and to maintain imperial hegemony in the right theatres. Add to this the recent domestic disasters and they’re crawling up the walls for it right now.
I don’t know if they really give a shit what their base think about it. A substantial number of them support single payer, and obviously they aren’t going to make that happen. A majority of them will support them regardless as long as they continue to oppose abortion. The alt-right weanies might not like it, but a) they really aren’t as statistically important as they or the rest of the internet think they are and b) they are just as pathetically partisan as anybody else on the right, and would probably salivate over slaughtering a bunch of socialists anyway.