But the opposition is split among factions backing different rivals in the Aug. 2 primary and over disagreements on who should attack Greitens or how, according to people involved in the discussions. They, like others interviewed for this article, spoke on the condition of anonymity to discuss sensitive matters.

Others are preparing to pour millions instead into an independent bid by John F. Wood, a senior investigative counsel on the House committee investigating the Jan. 6 attack. And some are concerned that intervening in the race could play into Greitens’s hands by feeding his anti-establishment posturing — or even prompting former president Donald Trump to endorse him.

Two people familiar with Trump’s reaction to the Greitens ad said the president expressed that he did not appreciate the content and believed it went too far. But Trump has not commented on the ad publicly, and he sometimes tells different advisers different things, depending on the context of the conversation.

Some Trump advisers have also been imploring him not to endorse Greitens, which could be decisive in the right-drifting state. Among those privately appalled by the ad is Ronna McDaniel, the Republican National Committee chairwoman, who has lobbied Trump against making any endorsement in the Missouri Senate race and made a round of calls to allies and advisers this week to express her displeasure with the video.