BOSSIER CITY, La. — President Trump urged Louisiana voters on Thursday to “send a message to the corrupt Democrats in Washington” by electing to governor the Republican nominee, Eddie Rispone, directly linking the impeachment inquiry to a state election that will test his clout in the Deep South.

Addressing supporters at his second rally in two weeks in heavily Republican north Louisiana, and his first since Democrats began public impeachment hearings, Mr. Trump dutifully read from his prepared text in an effort to rouse conservatives ahead of Saturday’s election.

“You will deliver a powerful rebuke to the socialists trying to demolish our democracy,” he told an arena full of enthusiasts here along the Red River.

But he also let slip his more personal interest in the Louisiana election, where Gov. John Bel Edwards is seeking re-election, by recalling negative headlines he had received this month in another race. Gov. Matt Bevin of Kentucky, a Republican, lost his re-election a day after Mr. Trump rallied supporters in the state.