As early in-person voting began on Saturday in Michigan, a fight for control of the G.O.P. in the crucial battleground state plunged Republicans there deeper into a political maelstrom, with rival factions potentially barreling toward hosting dueling nominating conventions.

As if things weren’t already confusing.

In a little over a week, the state will host a traditional primary on one day, and then a caucus-style convention a few days later. Now, it seems, there could actually be two conventions, in different parts of the state, each claiming legitimacy.

Former President Donald J. Trump is headed to Michigan on Saturday night, with a campaign rally in Waterford Township, about 30 miles northwest of Detroit. While he has made it clear which faction he is supporting, and so has the national party, that has done little to dissuade the Trump-styled election denier attempting to hold on to power.

The feud, already being waged in state court, appears to be only gaining intensity.

Pete Hoekstra, whom the Republican National Committee recognized on Wednesday as the state party’s rightful chairman after his election last month, said he was moving forward with plans to hold a statewide nominating convention on March 2 in Western Michigan.

But Kristina Karamo, defying the R.N.C.’s determination that she had properly been removed as party chairwoman earlier in January and Mr. Trump’s endorsement of Mr. Hoekstra, has also indicated that she will continue hosting a convention on the same day, for the same purpose, but in Detroit.

At stake at the convention will be 39 of Michigan’s 55 Republican presidential delegates. The other 16 will be decided during the state’s Feb. 27 primary, which includes at least nine days of early voting. The hybrid process, new this year, was adopted by Republicans in order to comply with R.N.C. rules after Michigan’s Democratic governor moved up the primary date.

“We are the Michigan G.O.P.,” Mr. Hoekstra said in an interview on Friday. “Kristina Karamo is not.”

Mr. Hoekstra, a former House member who was Mr. Trump’s ambassador to the Netherlands, referred to Ms. Karamo’s gathering on March 2 as a “meeting.”

“They’re not running a convention,” he said.

Ms. Karamo, who gained notoriety for her claims of fraud in the 2020 election, was elected as the party chair last year, after losing her 2022 bid for secretary of state. She did not respond to several requests for comment on Friday, but on social media and in a recent statement from the state party’s email account, she has insisted that she is still in charge.

“The Grey Poupon Good Ole’ boys club hate that they can’t control me, and that we’ve disrupted their corruption club,” Ms. Karamo wrote on Friday on X. “Our movement isn’t going away. We are bringing a Righteous Renaissance to the Republican Party.”

Critics of Ms. Karamo said that the Michigan party had been shrouded in secrecy under her leadership and was struggling with money.

On Thursday night, Ms. Karamo sought to address her leadership status at a Republican gathering in Oakland County near Detroit. A video recorded by The Detroit News showed her being heckled as party leaders elected delegates for next month’s state convention. Some shouted that she was “out of order” and was no longer the party’s chairwoman.

The clash was playing out in the western part of the state too, where rival Republican factions in Kalamazoo County held dueling party conventions at the same time on Thursday.

Inside a community center in Scotts, Mich., a small town near Kalamazoo, a faction aligned with Ms. Karamo elected 44 delegates to send to the March 2 convention in Detroit. About 15 miles away at the 12th Street Baptist Church in Kalamazoo, the other faction elected 44 delegates to send to the convention that Mr. Hoekstra is organizing.

“It’s crazy,” Fred Krymis said in the church’s lobby.

At the Karamo-aligned event, a projector displayed a logo for the county’s Republican Party. A sign advised that outsider observers were not allowed to record the proceedings because of intraparty lawsuits. A county sheriff’s deputy was on guard, watching for violators.

In a brief interview outside the event, Rod Halcomb, the group’s chairman, described Ms. Karamo as the “legitimate” leader of the Michigan Republicans and said he believed the R.N.C.’s recognition of Mr. Hoekstra was “an incorrect decision.”

But at the other gathering, Kelly Sackett, that group’s chairwoman, said that it was time for the party to unite behind Mr. Hoekstra.

“That’s the only way we’re going to take our state back,” she said of Republicans, who do not control any statewide offices.

The division at the state level is being mirrored by the two Kalamazoo groups, which are embroiled in a series of lawsuits accusing each other of defamation and of hijacking the party’s name and likeness.

Matthew DePerno, whom Ms. Karamo defeated for party chair last year, is part of the Kalamazoo faction that has coalesced around Mr. Hoekstra. An unsuccessful candidate for state attorney general in 2022, he was charged last year in an election equipment breach in 2020, one intended to help Mr. Trump reverse his loss in Michigan.

He mused on Thursday night that the party turmoil could boil over at the Republican National Convention this summer.

“I believe there will be probably two sets of delegates sent,” he said of Michigan’s representation.

The R.N.C. did not immediately respond to requests for comment about what would happen if rival slates of Michigan delegates showed up at the convention.

Mr. Hoekstra said that he had no illusions about the party he is seeking to lead.

“I understand and I know that these divisions exist,” he said. “I am not going to let them dominate, you know, our activities and our process over the next eight months. Our job is to win elections.”