The Soviet Union was not a multi-party democracy so I agree with you but it’s not relevant to the point I was making. With respect to the US, my guess is what‘s happened is both parties have drifted in the same direction, so the position of the “centre” (in the absence of mandatory voting defined as the median between the two parties rather than the median of the population) has moved too. Of course, I only have remote observer status - I’m not living it like most of those present in this discussion are.