If you want to speculate on the threat of the dreaded Socialists \ Communists running for office, at least consider some of the open white nationalists that are running for office recently such as Patrick Little and Joey Gibson. Oh and lets not forget Authur Jones. Yeah that guy who used to head the American Nazi Party who ran unopposed in the GOP Primary for Illinois.
Also, please don't lie to yourself and say that white nationalists are not violent people. I can provide ample evidence of white nationalists actually killing people. Multiple people in a few different countries. In terms of active threats to Americans, white nationalists top every list. They have killed more people than muslim extremists and leftists.