INDIANAPOLIS—Several Republican state senators who opposed a redistricting plan backed by President Donald Trump lost primary election challenges on May 5 to candidates endorsed by the president. Twenty-one GOP senators had voted against the redistricting plan, some citing lack of support for it in their districts and suspicion of Washington-based insiders meddling in state politics. Trump endorsed challengers in seven races where those senators faced primary opposition. In Indiana’s congressional races, incumbents fared better. Six easily overcame primary challengers as three others ran unopposed. Trump favored a congressional redistricting plan that would have redrawn the electoral map to favor Republicans in the two congressional seats now held by Democrats. Vice President JD Vance made two trips to the state to lobby for the plan. Gov. Mike Braun also strongly supported it....