President Donald Trump’s drive for political revenge faces a key test Saturday in Louisiana, where he is looking to defeat Republican Sen. Bill Cassidy five years after Cassidy voted to convict him in his second impeachment.

Sen. Bill Cassidy of Louisiana faces two challengers — one endorsed by the president — in Saturday’s primary, five years after voting to convict Trump.

Louisiana voters will participate in a revamped and stripped-down state primary Saturday and decide the political fate of an embattled Republican U.S. senator targeted for defeat…