Louisiana’s governor, John Bel Edwards, told supporters to brace for a barrage of national Republican efforts trying to unseat him, in the five weeks leading to a runoff election.

The deep south’s only Democratic governor fell below 50% voter support on Saturday night and was forced into a 16 November run-off against Republican businessman Eddie Rispone.

Donald Trump held an election eve rally urging Louisiana’s voters to reject Edwards. The president took credit on Twitter for keeping Edwards from a primary victory, and praised Rispone.

“The media is not talking about the big Republican victory last night in Louisiana,” Trump tweeted on Sunday, “where a sitting Democrat Governor was forced into a runoff by not getting 50%. Big upset! Now Eddie Rispone who will be a great Governor, will win!”

Edwards told supporters: “We’ve got a little more work to do.” But he said he believes Louisiana voters will embrace the spirit of bipartisanship in November and re-elect him.

Edwards needs cross-party support to win in ruby red Louisiana. He ran on bipartisanship, saying he worked across party lines on all the major initiatives he achieved in his first term in office.

Rispone saw off another Republican, US representative Ralph Abraham, to make the runoff. Trump backed both men.