The Democrats don’t want Robert F. Kennedy Jr. on the ballot. In early March, the Kennedy campaign announced that volunteers had collected over 15,000 signatures for the candidate’s name to appear in the voting booths of the swing state of Nevada. Later that month, Cisco Aguilar, the state’s Democratic secretary of state, threw cold water on the campaign’s excitement by rejecting the campaign’s signatures for having failed to include a running mate on the candidacy petition.  Kennedy’s...