antiparty

adj

1. Opposing a particular political party.

   “"They said that I had contacted foreign media and called me anti-China, antipeople and antiparty."”

noun

1. A political party that shuns or rejects the mainstream political establishment.

   “Differences arise over what kinds of organization are desirable (eg, political parties or antiparties, professionalized organizations, decentralized networks, communes, grassroots groups) and over tactical questions of what is to be done[…]”