“The latest revelations that hit this morning will upend his candidacy and will mean catastrophic shrinkage in his effort,” said Peter Kinder, a Republican former Missouri lieutenant governor who is supporting one of Greitens’s opponents, Representative Vicky Hartzler. The other major contender in the Republican primary is Attorney General Eric Schmitt, who has the backing of some in the state party establishment.

There are some signs that Greitens’s support is softening. The latest public poll of the primary, by the Trafalgar Group, showed Greitens falling into second place among likely primary voters for the first time. Another recent survey commissioned by Schmitt’s campaign showed similar results. And on Saturday, in what some saw as evidence of his growing difficulties, Greitens skipped a Republican Party event in Taney County, one of the bigger annual gatherings of activists in the state.

The turmoil in the Republican primary has complicated Donald Trump’s efforts to influence the outcome. Some party insiders had feared that Trump would endorse Greitens, who has tailored his campaign message around “defending President Trump’s ‘America First’ policies” and has questioned the 2020 presidential election results.