Oklahoma held primary elections on Tuesday for both a U.S. Senate seat and the governorship, offering a fresh gauge of President Donald Trump's influence as a Republican kingmaker ahead of November's midterm elections. Trump backed Rep. Kevin Hern for the Senate seat vacated when Markwayne Mullin joined the cabinet as Homeland Security Secretary, while his late endorsement of former state Sen. Mike Mazzei in a crowded gubernatorial field — which also includes Attorney General Gentner Drummond and former House Speaker Charles McCall — is seen as the steeper test. With candidates largely self-funding a combined $31 million race, no contender is guaranteed to clear the 50% threshold required to avoid an August runoff.