Right now only 10% of registered voters participate in the primaries and these tend to be the most extremely radical elements of the parties. This may be why our Congress people seem so far apart in key issues on which we need to compromise. They are all catering to the radical members of their base. If instead the primaries involved the vast majority of us who want reasonably negotiated legislation we might see bipartisan legislation. I seriously doubt that Trump ever would have even been nominated if we’d had mail in primaries