January 15 was the deadline for Mississippi presidential primary candidates, and for other office as well. Three Republicans will be on the presidential primary ballot: President Donald Trump, Rocky De La Fuente, and William Weld.
The Democratic presidential primary ballot will include ten names: Joe Biden, Michael Bloomberg, Pete Buttigieg, Tulsi Gabbard, Amy Klobuchar, Deval Patrick, Bernie Sanders, Tom Steyer, Elizabeth Warren, and Andrew Yang. Candidates got on the Democratic ballot by paying a fee of $2,500, and submitting 500 signatures. Any registered voter could sign. Thanks to Jim Riley for mention of the mandatory petition.
For the congressional races, no minor party has any candidates, except that the Libertarian Party has a candidate for U.S. Senate. See the list here.