There’s a growing right wing opposition to NATO

But that's not actual opposition to NATO or US wars in general. They are just opposing what the democrats are currently doing until they get elected again. These people very much want and are working towards US hegemony and open war with China, not just this proxy war against Russia. They do not want multipolarity and their appeals to Putin don't really mean anything. They're just part of a larger effort to be as contrarian as possible to the current democrat positions in public, while actually pursuing largely the same foreign policy as the democrats. There's also the factor of Trump "being friends" or whatever with Putin which is nonsense, but the republicans seem to like spreading that, if nothing else, just to piss off the democrats.

this puts Democrats in a dangerous and weakened position.

I don't really care what kind of position the democrats are in and neither should you. Both parties have the same imperialist and hegemonic policy and serve military-industrial, and other large corporation's shareholders' interests. The dems are not better than the republicans, and the US elections don't really decide anything. No one in the US should be allying with democrats (or republicans or relying on elections) and expecting achieve any sort of meaningful anti-imperialist changes.

I’d be interested to see what instances you’re referring to in terms of the SU and China allying with other imperialist forces.

I'm not talking about the Molotov–Ribbentrop pact, that wasn't an act of allyship. I'm talking about the larger picture of WW2 in general. The USSR, along with the UK and US fought the Nazis in Europe, and the communists in China formed temporary alliances with capitalist/feudalist forces which were funded by US imperialists to fight against Japan.

expecting Putin to liberate us from NATO

Again, my point is that no one is actually expecting this. Maybe a few fringe voices, but its far from a real position taken by people.