According to this story, Arthur Jones, who is on the ballot in the Illinois Republican primary for Congress in the 3rd district, is a former National Socialist White People’s Party activist. That is one of the U.S. groups that generally have been considered adherents to Nazi doctrines.
The 3rd Illinois district is now represented by Democratic Congressman Dan Lipinski. It covers part of Chicago and some of its Cook County suburbs. Jones is one of three Republicans on the primary ballot. The article says Jones would rather have run under another party name, but because it took 600 signatures to get on the Republican primary ballot, versus 5,000 to run as an independent, he chose the Republican primary route.