Mississippi has two U.S. Senate elections this year. The full-term race is a partisan race, but the special election for the other seat is a non-partisan race, with no party labels and no party nominees. In the special election, there are two Republicans running and two Democrats running, with a runoff if no one gets a majority in November.
Here is the November 2018 ballot, which has the US Senate full term race listed first, followed by the special election for the other seat. The two Republicans are appointed incumbent Cindy Hyde-Smith and Chris McDaniel. The two Democrats are Mike Espy and Tobey Bernard Bartee.