For Republican supporters of Donald J. Trump in Michigan, it seemed like a crowning moment: The state party chose two candidates endorsed by the former president, both outspoken preachers of 2020 election falsehoods, as its contenders for the state’s top law enforcement officer and its chief of election administration.But instead, that move at a convention last weekend — where Republicans officially endorsed Matthew DePerno for attorney general and Kristina Karamo for secretary of state — has ruptured the Michigan Republican Party. After months of strain, it appears to finally be snapping as what remains of the old guard protests the party’s direction.This week, Tony Daunt, a powerful figure in Michigan politics with close ties to the influential donor network of the DeVos family, resigned from the G.O.P.’s state committee in a blistering letter, calling Mr. Trump “a deranged narcissist.” Major donors to the state party indicated that they would direct their money elsewhere. And one of Mr. Trump’s most loyal defenders in the State Legislature was kicked out of the House Republican caucus.The repudiation of the election-denying wing of the party by other Republicans in Michigan represents rare public pushback from conservatives against Mr. Trump’s attempts to force candidates across the country to support his claims of a rigged 2020 vote. That stance has become a litmus test for G.O.P. politicians up and down the ballot as Mr. Trump adds to his slate of more than 150 endorsements this election cycle.Yet some Republicans in Michigan and beyond worry that a singular, backward-looking focus on the 2020 election is a losing message for the party in November.“Rather than distancing themselves from this undisciplined loser,” Mr. Daunt wrote in his resignation letter, “far too many Republican ‘leaders’ have decided that encouraging his delusional lies — and, even worse — cynically appeasing him despite knowing they are lies, is the easiest path to ensuring their continued hold on power, general election consequences be damned.“Whether it’s misguided true belief, cynical cowardice, or just plain old grift and avarice,” Mr. Daunt continued in the letter, which was addressed to a Republican colleague, “it’s a losing strategy and I cannot serve on the governing board of a party that’s too stupid to see that.”Mr. Daunt’s resignation shocked party insiders in Michigan, in part because of his close ties to Dick and Betsy DeVos, prominent conservative donors who have often acted as kingmakers in state Republican politics and have marshaled millions of dollars through their political arm, the Michigan Freedom Fund. Ms. DeVos served in Mr. Trump’s cabinet as education secretary.Jeff Timmer, a former executive director of the Michigan Republican Party and critic of Mr. Trump, said of Mr. Daunt’s letter, “Him taking a step like this is indicative of where their thinking is.” Mr. Timmer added, “It seems highly unlikely that he would do this and tell them afterward when they read it in the press.”A spokesman for the Michigan Freedom Fund did not respond to a request for comment. But some people within the DeVos network have also expressed frustrations about the direction of the state party, though they still want Republicans to do well in November, according to two people who have spoken with donors connected to the network and who insisted on anonymity to discuss private conversations.Betsy DeVos, the former education secretary, and her husband, Dick DeVos, at a White House event in 2019.T.J. Kirkpatrick for The New York TimesIn an interview on Thursday morning, Mr. Trump disputed that a lasting focus on the 2020 election might hurt Republicans in November.“I think it’s good for the general election because it’s made people very angry to get out and vote,” he said. He declined to say whether he would provide financial backing for Mr. DePerno or Ms. Karamo, though he praised Mr. DePerno as a “bulldog” and called Ms. Karamo “magnetic.”A Guide to the 2022 Midterm ElectionsMidterms Begin: The 2022 election season is underway. See the full primary calendar and a detailed state-by-state breakdown.In the Senate: Democrats have a razor-thin margin that could be upended with a single loss. Here are the four incumbents most at risk.In the House: Republicans and Democrats are seeking to gain an edge through redistricting and gerrymandering, though this year’s map is poised to be surprisingly fairGovernors’ Races: Georgia’s contest will be at the center of the political universe, but there are several important races across the country.Key Issues: Inflation, the pandemic, abortion and voting rights are expected to be among this election cycle’s defining topics.Mr. Trump declined to comment on the DeVos network, saying only of Ms. DeVos, who resigned from his administration after the Capitol riot, “She was fine, but the one that I really liked in that family was the father, who was essentially the founder.” (Ms. DeVos’s father, Richard M. DeVos, who died in 2018, was also a major Republican donor.)The most recent campaign-finance reports for the state party show that some big-dollar contributors have shifted their giving.“A lot of the traditional donors, they just walked away,” said John Truscott, a Republican strategist in Michigan. “I don’t know how it survives long term.”By the end of 2021, campaign finance reports show, the number of direct contributions greater than $25,000 to the Michigan Republicans had dwindled. The money the party took in included $175,000 in November from Ron Weiser, the party’s megadonor chairman.Mr. Weiser, who drew criticism last year when he joked about assassinating two Republican congressmen who voted to impeach Mr. Trump, gave the party at least $1.3 million for the cycle, according to the reports.In an email on Wednesday, Gustavo Portela, a spokesman for the Michigan Republican Party, said it was financially sound and cited the generosity of Mr. Weiser, saying he had committed to give and raise “the money we believe is necessary in order to win in November.”Ron Weiser, the chairman of the Michigan Republican Party, is also a major donor who has pumped cash into the party.David Guralnick/Detroit News, via Associated PressBut the names of other prolific donors, like Jeffrey Cappo, an auto-dealership magnate and philanthropist, no longer appeared in the reports for late 2021.Mr. Cappo said on Wednesday that he had found other avenues to give money to Republicans.“Our political state,” Mr. Cappo said, “is more dysfunctional than it’s ever been.”He said of Mr. Trump, “I think the guy really, really cared, but he cares more about himself than anybody else.”Republican divisions had been growing for weeks before the state party convention last weekend. And frustrations with Meshawn Maddock, a co-chair of the state party with close ties to Mr. Trump, boiled over as she endorsed candidates before the convention, including Mr. DePerno and Ms. Karamo.Mr. DePerno, a lawyer who challenged the election results in Antrim County, has pledged to investigate “all the fraud that occurred in this election,” including inquiries of Gov. Gretchen Whitmer, Secretary of State Jocelyn Benson and Attorney General Dana Nessel, all Democrats.Ms. Karamo rose to prominence after challenging the state’s 2020 results as a poll worker, arguing that she had witnessed fraud. Her claims were later debunked, but she quickly gained fame in conservative circles.When Mr. DePerno and Ms. Karamo all but clinched their nominations, it was not through a traditional party primary. Michigan instead nominates many statewide offices through a convention system, in which party activists serve as “precinct chairs” and vote on the nomination.The campaigns for Ms. Karamo and Mr. DePerno did not respond to requests for comment.Amid the fallout from the convention, Matt Maddock, a Republican state representative whom Mr. Trump had supported to become speaker next year, was pushed out of the House Republican caucus this week.Matt Maddock and Meshawn Maddock have been power players in Michigan Republican politics. Emily Elconin/ReutersA spokesman for Jason Wentworth, the current State House speaker and a Republican, confirmed in an email on Wednesday that Mr. Maddock had been “removed” from the Republican caucus. He declined to give a reason, saying he was not authorized to discuss internal business. On the website of the Michigan House Republicans, a member page for Mr. Maddock had been removed.Mr. Maddock’s campaign did not respond to requests for comment. Nor did Ms. Maddock, a chairwoman of the Michigan Republican Party and Mr. Maddock’s wife. The Maddocks had been vocal supporters of Trump-aligned Republican candidates before the convention, including some Republican challengers to incumbents in the Legislature.“When you’re a member of a team, you can’t expect the benefit of being on that team while you’re simultaneously trying to trip your teammates,” said Jase Bolger, a Republican former speaker of the Michigan House. “So it wouldn’t be reasonable to expect him to remain on that team while he’s out actively opposing his teammates.”Removing Mr. Maddock from the House Republican caucus does not doom his re-election chances, but it will make it harder for him to raise money and maintain influence. Of course, outside money from groups allied with Mr. Trump could help offset any loss in fund-raising for Mr. Maddock, the state party or other candidates aligned with the former president.Despite the chaos, veteran Michigan Republicans are still bullish on the coming elections, provided the party’s message shifts.“We need to return to focusing on issues, on principles, on empowering people and turn away from the divisiveness and personalities,” Mr. Bolger said, “and certainly need to focus on 2022 and not 2020.” More