Donald Trump has endorsed former college football coach Tommy Tuberville over his former attorney general Jeff Sessions in Alabama's US senate race.

The seat is currently held by Democratic Senator Doug Jones.

Mr Sessions faces a runoff election with Mr Tuberville for the Republican candidacy on 31 March, following a narrow primary election on 3 March.

The president forced the former US attorney general to resign after he had recused himself from the Justice Department's impeachment inquiry into foreign interference in US elections.

His ongoing criticism and "disappointment" with his attorney general — saying "I don't have an attorney general, it's very sad" — prompted Mr Sessions' departure from the administration in 2018.

Mr Tuberville coached at the University of Mississippi, Auburn University, Texas Tech University and University of Cincinnati before making a political turn, announcing his entry in a race to unseat incumbent Jones, who was elected to the US Senate in 2017 in a special election.

Mr Jones, who defeated Roy Moore in that race, is one of two Democratic senators facing reelection to the US Senate in 2020.

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On Twitter, the president said Mr Tuberville "is a REAL LEADER who will never let [Make America Great Again and Keep America Great], or our Country, down!"