It's unfortunate that in today's state of American Politics the political parties have forgotten that there use to be ideologically impure positions to have which made politicians and people active in politics sensible moderates such as being "Progressive Republicans" and "Conservative Democrats".
It's a shame that if politicians and politically active people were to be behave like that again they would be accused of selling-out to the other side and savaged by their own side for not being ideologically pure enough which is not healthy for politics and makes it very dogmatic and rigid with no flexibility at all
However it must also be said that both sides are not equally at fault because the Center-RIGHT went somewhat to the RIGHT whereas the Center-LEFT went beyond further LEFT to the point it became an straight-up Neo-Communism position causing the old Center-LEFT become by today's standards the new Center-RIGHT by default thus the LEFT is significantly more at fault in this shifting of positions in the Political Spectrum
Just imagine if we had Pro-Strict-Policing Democrats elected by Progressives and Pro-Choice Republicans elected by Conservatives today it would be considered as "Political Heresy" or "Politically Sacrilegious" or "Political Blasphemy" now