The District of Columbia presidential primary is the latest in the nation, June 14. That is so late, the Republican Party decided to use a caucus in D.C. instead. January 4, 2016 was the deadline for Republicans to qualify for the caucus. They either had to pay a fee of $15,000; or they had to pay $7,500 and submit 150 signatures of registered Republicans.
Three candidates collected signatures: Jeb Bush, John Kasich, and Marco Rubio. Seven other candidates paid the larger fee and skipped the petition: Ben Carson, Chris Christie, Ted Cruz, Carly Fiorina, Rand Paul, Rick Santorum, and Donald Trump. Thanks to Michael Beckel for the news.