Is Trump's hold on the GOP waning? We’re about to find out.

A former president who famously claimed he would win so much that his followers would be "sick and tired of winning" faces the prospect of something new within normally friendly terrain: a losing streak.

Starting next month, in states from Georgia and North Carolina to Arizona and Alaska, former President Donald Trump will see his influence tested in a series of high-stakes GOP primaries.

Trump has placed himself in the middle of a wide range of races in which his chosen candidates have struggled or where he is at sharp odds with other prominent Republican voices -- including former Cabinet members, close aides and potential rivals who hope bad calls by Trump prove a point.

"Trump is trying to insert himself in races all across the country where people he's supporting are crazy," Maryland Gov. Larry Hogan, a Republican, told ABC News.

"The primaries are critically important because they are going to determine what the Republican Party looks like," said Hogan, who leaves office at the end of the year and is supporting a series of candidates whom Trump is actively trying to beat. "It will tell us how much Trump's influence has waned or not. Has he been diminished? And what does that foretell about the next election two years later?"

In one recent sign of how little some Republicans now fear Trump's wrath, New Hampshire Gov. Chris Sununu appeared at Washington's Gridiron Club dinner over the weekend and labeled Trump "f---ing crazy." Sununu, who later called his speech "all in fun" and "all a joke," is up for reelection in a state that delivered Trump his first primary win of 2016.

Trump is still widely seen as the loudest and most powerful force in Republican politics. Candidates and potential candidates have been parading to Mar-a-Lago virtually since Trump left office in search of what the former president bills as his "complete and total endorsement."

"There's nothing more powerful in American politics than the endorsement of President Trump," Taylor Budowich, a Trump spokesman, said in a statement. "The MAGA ticket is going to sweep the midterms, as voters everywhere look to restore the policies and leadership of President Trump."

But that outcome is not guaranteed. Trump is putting significant political capital on the line by endorsing and pushing candidates who have pledged fealty to him and to his lies about the last election -- and who could very well lose primaries, according to a range of strategists and some of his highest-profile critics inside the party.

When Trump takes the stage for his next rally Saturday night in North Carolina, top billing will go to a unique group of candidates whose endorsements by Trump have roiled local and national politics.

In the state's open Senate race, Trump was not able to clear the field for Rep. Ted Budd, who was staunchly loyal to Trump through Jan. 6 and beyond. Budd is facing former Gov. Pat McCrory, as well as a Trump-friendly former House member, in a crowded race that could be headed to a runoff after the first round of voting on May 17.

Rep. Madison Cawthorn briefly flirted with running in a different congressional district and more recently lost the support of both of North Carolina's GOP senators after a bizarre interview in which he alleged his colleagues used cocaine and organized orgies.

Trump will also stand beside another 26-year-old House candidate, Bo Hines, a former college football wide receiver and political newcomer who lives two hours away from the newly created district he's running in. With Trump set to visit their part of the state, local pro-Trump activists are scrambling to sink Hines' candidacy, Politico reported Thursday.

"We're all America First people, but we don't need Mr. Trump or anybody else bringing candidates in who don't know nothing about farming, don't know anything about agriculture and the roads here and the needs we have," one local activist told Politico.

Trump's sway will face an indirect but closely watched test May 3 in Ohio, where Trump hasn't endorsed in the highest-profile races but where former Rep. Jim Renacci has campaigned for governor citing his endorsement by Trump in a 2018 race. Public polls have consistently shown incumbent Gov. Mike DeWine leading comfortably, with Renacci sometimes running third in the four-way field.

The highest-profile measure of Trump's influence might come May 24 in Georgia. Trump has made it his mission to bring down Gov. Brian Kemp and Secretary of State Brad Raffensperger -- conservative Republicans who backed Trump in 2020 but refused his demand to overturn his loss to President Joe Biden.

"Before we can defeat the Democrat socialists and communists," Trump said at a rally in Georgia last month, "we first have to defeat the RINO sellouts and the losers in the primaries this spring."

Trump convinced former Sen. David Perdue to run against Kemp in the GOP primary, a race in which the Democratic candidate will likely be Stacey Abrams. Kemp just wrapped a legislative session filled with conservative victories, and a recent Fox News poll showed him with an 11-point lead over Perdue.

Trump is backing Rep. Jody Hice against Raffensperger. But his "Boot Brad" campaign has had to explain why the congressman posted and then deleted a social media message calling Jan. 6 "our 1776 moment" while the riot at the Capitol was still ongoing. As recently as a few weeks ago, Hice was caught on camera appearing to commit to decertifying the 2020 election if he assumes office.

Lt. Gov. Geoff Duncan, R-Ga., told ABC that additional Trump losses in Georgia would mark a blow to the former president and his insistence that fighting over a lost election is a winning strategy.

"It will certainly send a message," said Duncan, who chose to leave office at the end of the year instead of enduring a bruising reelection campaign. "It's pretty obvious to all the factions of the Republican Party here in Georgia that Trump's endorsement is transitioning from a tailwind to a headwind."

Trump has chalked up notable victories over perceived political enemies since leaving office. This week, Rep. Fred Upton, R-Mich., became the fourth impeachment-supporting Republican to announce his retirement rather than face reelection: "4 down and 6 to go," Trump said in a statement.

Trump endorsements still have "unique and tremendous impact," said David McIntosh, president of the conservative Club for Growth. But he added that candidates have to carry their own weight, and the fact that Trump no longer has access to the biggest social-media outlets means outside groups like his have to reinforce endorsements with advertising in ways that were less vital when Trump tweets drove news cycles.

"The candidate has to do their part -- run hard, run a good campaign, message well," said McIntosh, whose group is spending heavily to help Budd and several other Trump-endorsed candidates, as well as some he's not backing. "Then the Trump endorsement is a big thing. It's like wind behind their sails."

But there are signs that Trump is getting nervous about some choices. Last month, with polls showing Rep. Mo Brooks falling behind rivals in the Alabama Senate race, Trump revoked his endorsement.

The former president has chosen not to endorse anyone in a number of upcoming contests in which several Republicans tout how close they are to him. There is no Trump-endorsed candidate running in upcoming Senate races in states including Missouri, Ohio, Arizona and Pennsylvania, a sign to some observers that Trump is afraid of choosing eventual losers.

Trump's initial choice in Pennsylvania dropped out after a child-custody dispute revealed allegations of domestic abuse. He is now staying out despite the fact that the candidates include David McCormick, who is the husband of his former top aide, Dina Powell and who has been endorsed by former Secretary of State Mike Pompeo and Sen. Ted Cruz, R-Texas; Trump is also close to other candidates there, including Dr. Mehmet Oz.

Where and how Trump has chosen to get involved has sometimes mystified and frustrated some of his loyalists. Last weekend in Michigan, Trump made fun of how Rep. Peter Meijer's name is pronounced, even though the name is plastered across a prominent chain of Midwestern department stores.

In South Carolina, Trump appears to have taken a special interest in defeating Rep. Nancy Mace, who was a vocal critic of Trump on and immediately following Jan. 6 but has since softened her critiques. Mace's backers include former South Carolina governor and United Nations ambassador Nikki Haley.

Mace responded to that move by filming a short video in front of Trump Tower in New York City where she sang Trump's praises and added a warning: "If you want to lose [this] seat once again in midterm election cycle to Democrats, then my opponent is more than qualified to do just that."

Republican Leader Kevin McCarthy and his political operation are supporting Meijer, Mace and Rep. Jaime Herrera Beutler, R-Wash., putting the possible future speaker on the opposite side of some of Trump's top targets. By contrast, McCarthy has abandoned Rep. Liz Cheney, R-Wyo., and is working with Trump on behalf of her main opponent in the state's August primary.

Trump's sway and reputation will be tested twice in Alaska this summer. Trump endorsed former Alaska Gov. Sarah Palin almost immediately after she joined a 48-person field for an open House race last week. The former president is also working to unseat Sen. Lisa Murkowski, R-Alaska, despite her history of surviving even after losing a primary.

Trump also endorsed Idaho's lieutenant governor in her primary against the incumbent Republican governor, after an odd power struggle in which the state's No. 2 executive changed COVID-19 policies when the governor left the state. That leaves Trump at cross-purposes with the Republican Governors Association, which backs its incumbents and is being forced to spend millions to shore up some of them against intraparty attacks.

In Texas, shortly after the first round of primary voting on March 1, Trump bragged that all 33 candidates he endorsed either came out on top or advanced to the next round. He omitted, though, a loss for his chosen candidate in a special House election last summer.

Perhaps his biggest gamble in the state is backing embattled incumbent Attorney General Ken Paxton in his reelection bid. Paxton, a leader in national legal efforts to overturn the election, will face off against Texas Land Commissioner George P. Bush -- the only prominent member of the Bush family to embrace Trump -- in a May 24 runoff where both candidates tout their ties to the former president.

Several Republican strategists who spoke with ABC News on condition of anonymity say Trump appears to them to have lost king-making status. While his endorsement alone could vault a candidate to office in previous cycles, his diminished megaphone and focus on relitigating 2020 hurt him when taking on established GOP figures, particularly those who don't define themselves as "never-Trump," they say.

In Maryland, where Hogan is term-limited, Trump has endorsed state Rep. Dan Cox for governor. Cox attended the Jan. 6 "Stop the Steal" rally in Washington and tweeted that day that then-Vice President Mike Pence was "a traitor."

Hogan has endorsed Kelly Schulz, his former secretary of commerce, whom he thinks stands the strongest chance in their blue-tinged state.

"I'd like to be able to say, you know, we won all these races -- and he lost," Hogan said. "He lost the White House and the Senate and the House and governors' races and state legislative bodies. I wouldn't call that being a winner. And now he's going to lose in 2022 -- another round of losses for him. And so that's something that can help us steer things in a better direction."

ABC News' Hannah Demissie and Alisa Wiersema contributed to this report.