New reporting confirms Republican Mike Mazzei, the Trump-backed former Oklahoma state senator and budget secretary, won Tuesday's gubernatorial runoff over state attorney general Gentner Drummond by a single point, in a race that had appeared far from settled beforehand. The contest became one of the nastiest of the election cycle and offered another test of Donald Trump's ability to sway Republican primaries in governor's races, an arena where his endorsements have traditionally carried less weight than in Senate or House contests.

The latest details reveal the scale of spending behind the race: Mazzei loaned his own campaign an Oklahoma-record $11.6 million and outspent Drummond overall, roughly $12.3 million to $9.1 million across the primary and runoff, while Drummond put in $3 million of his own money but drew more from outside donors. Nearly $13 million more was spent by outside groups since 1 July, including over $3 million from the Club for Growth-linked School Freedom Fund attacking Drummond over his stance on Trump's impeachment, and close to $3 million from the rival Put Oklahoma 1st PAC targeting Mazzei over past support for tax rises. The campaign was also marked by a bitter row over health and drug-testing records, triggered by a debate exchange, in which Drummond released his medical records and a clean drug test and challenged Mazzei to do the same; Mazzei's own clean test followed, but Drummond argued it wasn't rigorous enough to detect longer-term substance use, an issue sharpened by Mazzei's serious 2008 car accident, which Mazzei says has not left him dependent on pain medication.