Also elected to leadership positions were two women, Marian Sheridan and Diane Shindlbeck, who along with Ms. Maddock formed Michigan Trump Republicans after he was elected in 2016. The group organized rallies, caravans and forums across the state to drum up support for his re-election bid.

“The Republican Party has evolved into the Trump party, and from the standpoint of Weiser, it brought a lot of new people into the party, and it’s his job to keep them there,” said Tom Shields, a Lansing-based Republican political consultant with Marketing Resource Group. “And using Meshawn as the conduit to the grass roots is smart.”

The race to lead the Michigan Republican Party was thrown into disarray this week when Ms. Cox, the current chair, took aim at Mr. Weiser for what she called a “sleazy payoff” to a party official to get him to drop out of the race for secretary of state in 2018.

Ms. Cox claimed that Mr. Weiser had sent $200,000 to Stan Grot, the clerk of Shelby Township in Macomb County, so that Mary Treder Lang would face no opposition for the Republican nomination for secretary of state, Ms. Cox said. She said it was not only unethical but could be a violation of state campaign finance laws. She turned over her complaint to the secretary of state, Jocelyn Benson, a Democrat, who could open an investigation into the state Republican Party.

“If you think what Ron did is OK, then vote for him,” Ms. Cox wrote in an email to party delegates on Thursday. “If you don’t want back room deals and secret payoffs, then vote for me.”

In a social media post, Mr. Weiser called the accusations from Ms. Cox “a shameful attempt to destroy our party with unfounded and reckless conspiracy theories so that she can get back in the chair’s race and save her paycheck.”

He said the money paid to Mr. Grot had been for organizing work he did in Macomb County, a key Republican stronghold, during the 2018 election cycle.