The power of former President Donald Trump’s endorsement will be put to the test on Tuesday, with his preferred candidates facing hotly contested Republican primary battles across the country.

Trump has waded into Senate, House and gubernatorial primaries in Maine, Nevada, North Dakota and South Carolina as he aims to further demonstrate his influence among the GOP base and shape the future of the party. Tuesday’s primaries also come less than two weeks after Trump was convicted of 34 felony counts in the New York hush money case. 

The presumptive Republican presidential nominee has notably sought to shore up two GOP members of Congress from South Carolina who are facing conservative challengers.

He is backing Rep. Nancy Mace, who had previously been critical of Trump, as she faces a well-funded primary opponent in attorney Catherine Templeton. After initially calling for the GOP to move on from Trump after the Jan. 6, 2021, Capitol riot, Mace won over her 2022 primary challenger, Katie Arrington, who had Trump’s endorsement.

Mace went on to ardently support Trump in the 2024 presidential primary and won his endorsement for re-election. While Trump’s support is coveted in GOP primaries, he lost Mace’s Charleston-area 1st Congressional District to Nikki Haley in February while winning the state’s primary overall. 

Mace drew the ire of some Republicans after voting to oust Kevin McCarthy as House speaker last year. Templeton has support from McCarthy, including donations from his leadership PAC, and she said that she asked the former California congressman to help her raise campaign cash.

Outside groups tied to McCarthy allies have also hit the airwaves to attack Mace, while the conservative Club for Growth Action has launched ads to boost Mace, according to the ad tracking firm AdImpact. Winning for Women Action Fund, a group that supports GOP women candidates and backed Mace in 2022, is now supporting Templeton. Longtime Rep. Joe Wilson, R-S.C., also endorsed Templeton last week over his House colleague.   

It’s possible this primary might not end on Tuesday. Mace, Templeton and Marine veteran Bill Young are on the ballot, meaning the race could be pushed to a June 25 runoff if no candidate wins a majority of the primary vote.

Trump has backed another incumbent facing a primary challenge: South Carolina Rep. William Timmons in the 4th District, which includes heavily evangelical parts of the state in Greenville and Spartanburg. 

Timmons is facing state Rep. Adam Morgan, who chairs the Freedom Caucus in the South Carolina state House and has endorsements from hard-right members of Congress such as Rep. Matt Gaetz of Florida and House Freedom Caucus Chairman Bob Good of Virginia.

Timmons has touted Trump’s endorsement in the race, launching an ad featuring the former president speaking directly to the camera to boost the three-term congressman. Timmons, who narrowly avoided a primary runoff in 2022, has had some help on the airwaves in this race from Defend American Jobs, a group tied to the cryptocurrency industry, and an outside group called America Leads Inc.

Timmons’ opponent in the 2022 primary, pastor Mark Burns, won almost a quarter of the vote. But Burns is now running with Trump’s endorsement in the open 3rd District race in South Carolina to replace retiring GOP Rep. Jeff Duncan. Trump also appeared in a TV ad for Burns reportedly filmed on the evening of April 19 at Trump Tower in New York City, the same day Trump was in court for his hush money trial. 

The 3rd District race is expected to go to a runoff given the crowded primary field. 

Burns, nurse Sheri Biggs and state Rep. Stewart Jones are considered the top candidates. The race also features Kevin Bishop, a former aide to South Carolina Sen. Lindsey Graham. 

Trump makes a last-minute pick in Nevada

Trump’s endorsement is also on the line in Nevada’s GOP Senate primary, where the winner will face Democratic Sen. Jacky Rosen in one of the top Senate races in the country. 

The top candidates in the crowded field are military veteran Sam Brown, who won Trump’s endorsement over the weekend, and Jeffrey Gunter, who served as Trump’s ambassador to Iceland at the end of his administration. 

Brown lost the Senate primary in the state in 2022 in an attempt to run to the right of former Attorney General Adam Laxalt, but has emerged in this race as the party-preferred pick to take on Rosen. He’s sought to soften his stance on abortion amid his wife’s decision to share how getting an abortion affected her life.

Gunter has played up his service in the Trump administration and tried to label Brown as insufficiently conservative. Gunter calls himself “110% pro-Trump,” a message that could be blunted by Trump’s late decision to put his thumb on the scale for his opponent.

Gunter has also run brutal attacks on the airwaves, including one that calls Brown “the newest creature to emerge from the swamp.” That ad colorizes the scars on Brown’s face he has after suffering severe burns in a life-threatening explosion while serving in Afghanistan. 

Brown has far and away been the biggest fundraiser in the race, outraising Gunter $7.1 million to $3.3 million while outspending him $4.6 million to $3 million as of May 22. But Gunter has outspent him on the airwaves 3-to-1. 

The endorsement may be muted by the fact that Trump waited until the weekend before the primary to announce his pick in a state that largely votes by mail. Plus, Brown had already been seen as the favorite. 

Further down the ballot, Trump has endorsed former North Las Vegas Mayor John Lee in the competitive 4th District to take on Democratic Rep. Steven Horsford. Democratic Reps. Susie Lee in the 3rd District and Dina Titus in the 1st District will also learn their GOP opponents on Tuesday, but Trump has not endorsed in either of those contests.

Trump and a VP contender take opposite sides

In North Dakota, Republican primary voters effectively are choosing a new governor after GOP Gov. Doug Burgum decided not to run for re-election. The state hasn’t elected a Democratic governor since the 1988 election and Trump won it in 2020 by more than 40 percentage points.

The GOP primary has been a contentious one between the state’s sole member of Congress, Rep. Kelly Armstrong, and Lt. Gov. Tammy Miller. Armstrong has the backing of Trump and both of the state’s U.S. senators, while Burgum, who Trump is considering as a running mate, is supporting Miller. 

While Burgum recently downplayed the idea he and Trump are on opposite sides, the race has gotten chippy. 

In a recent ad, Miller took a not-so-veiled shot at her top opponent by criticizing “self-serving politicians,” and saying: “No one gave me a ladder to get there. Climbing the ladder is what entitled politicians do, and they’ll step on anyone to come out on top.” 

Meanwhile, Armstrong’s campaign ran an ad warning that Miller has “way too many red flags,” criticizing her for a handful of small donations in the past to Democrats. 

State Sen. Merrill Piepkorn is the only Democrat running for governor and will face off against the winner of the GOP primary. 

Armstrong’s bid leaves his at-large House seat open, giving North Dakotans another statewide primary to decide on Tuesday’s ballot. The top candidates are state Public Service Commissioner Julie Fedorchak, who is endorsed by Trump, Burgum and GOP Sen. John Hoeven; former state Rep. Rick Becker, a former plastic surgeon backed by conservative figures like Ron and Rand Paul, House Freedom Caucus Chairman Bob Good and the Club for Growth; and Alex Balazs, a veteran who has the state party’s endorsement. 

Most of the oxygen has been taken up by Becker and Fedorchak, the top fundraising candidates in the race and those whose allies have dominated the airwaves. 

The Club for Growth has spent more than $700,000 on the airwaves in the race, largely blasting Fedorchak. But the group canceled its ad buys after Trump’s endorsement, and Fedorchak’s allies have largely matched the club’s spending while lobbing attacks against Becker. 

Meanwhile, in Maine, Trump issued an endorsement in the GOP primary for the competitive 2nd District, where Rep. Jared Golden is one of five Democrats running for re-election in a district Trump carried in 2020. The former president backed state Rep. Austin Theriault, a former NASCAR driver. 

GOP poised to pad House majority in Ohio special election 

Voters in Ohio will send a new member to Congress in a special election for the seat vacated by former GOP Rep. Bill Johnson earlier this year.

Republican state Sen. Michael Rulli is the favorite to serve out the remainder of the term in Ohio’s 6th District, which Johnson won by 35 points in 2022 and Trump won by almost 30 points in 2020, according to data compiled by Daily Kos Elections. His state Senate district is in the Youngstown area, which is part of the congressional district, and his family owns grocery stores in the area. 

Democrats have nominated Michael Kripchak, an Army veteran and retired police officer. But Rulli’s been the overwhelming leader in fundraising in the deep-red district. A GOP victory here would help pad Republicans’ slim majority in the House. 

Special elections in these kinds of districts are typically low-turnout affairs. But all eyes may be on this area again in the fall, even if the congressional district isn’t expected to change hands. That’s because the Youngstown area will be key for Ohio Democratic Sen. Sherrod Brown in his attempt to win re-election in a year Trump is expected to hold the state at the top of the ticket.