Former President Donald J. Trump capped off a clean sweep of Republican delegates in Michigan on Saturday during a raucous convention, which further exposed a deep fissure in the state party that threatens to fester in one of the most important battleground states.
Mr. Trump, the Republican front-runner, amassed at least 90 percent of the vote in all but one of the state’s 13 congressional districts against former Gov. Nikki Haley of South Carolina, who was ambassador to the United Nations under Mr. Trump.
A simple majority was needed in each district to win its share of delegates at the caucus-style event, giving Mr. Trump 39, to go along with the 12 that he won in Michigan’s primary, which was held on Tuesday. Ms. Haley emerged from that contest with four delegates.
Mr. Trump’s dominance earlier in the week left little doubt about the outcome of the convention on Saturday at the Amway Grand Plaza in Grand Rapids, Mich.
But a protracted fight over the state party’s rightful leader spilled over into the proceedings, where an estimated 200 Republican stalwarts from about 20 of Michigan’s 83 counties were denied credentials. Two other groups boycotted the event and held breakaway conventions, one more than 100 miles to the north in Houghton Lake, Mich., and another more than 50 miles southeast in Battle Creek, Mich.
Many of those denied credentials were people aligned with Kristina Karamo, whom party leaders in January voted to remove as the state party’s chairwoman. They replaced her with Pete Hoekstra, a former U.S. representative who was Mr. Trump’s ambassador to the Netherlands.
Not all of Ms. Karamo’s backers were shut out on Saturday: A group from Saginaw County jeered and made thumbs-down gestures when Mr. Hoekstra spoke. He acknowledged the friction.
“It can be a little bit abusive,” Mr. Hoekstra told delegates during one of the caucuses, which took place in a ballroom replete with a chandelier and a portrait of President Gerald R. Ford, an old-guard Republican who was raised in Grand Rapids.
Mr. Hoekstra, speaking to reporters, denied that the credentialing snub was an act of retribution, saying that those groups had not properly registered for the convention.
Ernest Dugan, a Saginaw County delegate and supporter of Ms. Karamo, said that he was disgusted by actions of party leaders, who have criticized the former chairwoman for money problems in the party and governance issues.
“The whole thing stinks to high you-know-where,” Mr. Dugan said.
As a Black Republican, he said he was troubled by the message that the party was sending with its ouster of Ms. Karamo, who is Black.
“A person of color wants to be in your group,” he said, adding, “Then you kick her to the curb?”
Until Friday, it had appeared that a rival convention, planned months ago by Ms. Karamo, might compete with the one organized by Mr. Hoekstra in Grand Rapids and recognized by the Republican National Committee. But after a series of court defeats disputing her removal as party chairwoman, Ms. Karamo scuttled her plans to hold the event in Detroit.
“We need to be united around Hoekstra,” said Jay A. Fedewa, chairman of the Genesee County Republican Party. “It’s disheartening that they don’t want to do that.”
Mr. Trump, whose victory in Michigan in the 2016 election propelled him to the presidency and who later lost the state to Joseph R. Biden Jr. in 2020, has recognized Mr. Hoekstra as chairman during the power struggle.
Debra Ell, a party leader from Saginaw County, compartmentalized her loyalty to Ms. Karamo and the former president.
“Almost everybody, honestly — we love Trump, by the way — but everybody that Trump has endorsed in Michigan has not won,” said Ms. Ell, who wore a pin with Ms. Karamo’s picture on it. “So bless his heart. We love him, but stay out of our politics.”
At the convention, where one delegate went into cardiac arrest, Mr. Trump outperformed his showing in the primary on Tuesday. Mr. Hoekstra attributed the former president’s sweep to the fact that the process was limited to Republicans. Primaries in Michigan are open to all voters, regardless of party affiliation.
“These folks are focused on winning in November,” he said. “Right? Not fighting other Republicans.”
Still, a woman holding a “Hoekstra Is an Impostor” sign lingered nearby.
At the breakaway gathering in Houghton Lake, about 300 Republicans who boycotted the Grand Rapids convention held their own vote to award delegates, a move Mr. Hoekstra and the R.N.C. have said won’t count. All votes went to Mr. Trump.
Daire Rendon, a former state representative who faces felony charges related to a voting-machine breach after the 2020 election — one intended to overturn Mr. Trump’s defeat in Michigan — presided over the event. She wore a blue Trump cap with a Q pin — for the QAnon conspiracy movement — on it.
“This is not going to impact the national election,” Ms. Rendon said. “But what it does is impact the party here in our state because what we’ve done is we’ve gone back to the party of the old white guys when we had a new grass-roots party being led by Kristina Karamo, who was the younger, dynamic version of a rebirth of the Republican Party, embracing a set of values that the Republican Party has always said it stood for.”
The breakaway group then held what amounted to a straw poll, asking supporters of Ms. Karamo to stand. They did the same for Mr. Hoekstra; no one stood for him.
“We have a unanimous vote,” Ms. Rendon said.
