Democrats are clinging to small leads in both states, and it may take quite a while until the winners are known.

© Christopher Miller for The New York Times

The race for U.S. Senate is close in Mississippi, which does not allow for vote recounts in statewide elections.

© Edmund D. Fountain for The New York Times

President Trump on Monday was the latest big political star to swing through Mississippi and boost a candidate in a red-state Senate race that suddenly seems competitive.

© Doug Mills/The New York Times