Mike Mazzei leads the Oklahoma Republican gubernatorial runoff market at 74% implied probability ahead of the August 25 vote, reflecting trader assessment of his Trump endorsement and stronger recent momentum following the June 16 primary where he and Attorney General Gentner Drummond narrowly advanced over Chip Keating and others. Mazzei, a former state senator and financial adviser, has benefited from substantial television advertising and alignment with national conservative priorities on taxes and education reform, while Drummond’s incumbency advantages as the state’s top law enforcement official have not translated into a polling edge in the head-to-head. A late-August survey showed the candidates statistically tied, underscoring how endorsements, turnout among Trump-aligned voters, and last-week messaging on issues like economic development and state spending will determine the nominee in this closely contested Republican primary.