Trump’s Grip on the GOP: 3 Primaries Testing His Power in 2026

Donald Trump’s longstanding influence over the Republican Party is facing several high-stakes tests during the May 2026 primary season, as voters in multiple states decide whether to follow the former president’s lead or defy his endorsements.

For years, Trump has maintained a dominant hold on the GOP ecosystem. According to Ballotpedia, in 2022, 93% of his endorsed candidates successfully navigated their primaries, and 83% won their general elections in November. By 2024, those figures rose to 96% for primary success and 89% for general election victories.

While some candidates—such as Governor Brian Kemp in Georgia, Senator Lisa Murkowski in Alaska, and Representative Nancy Mace in South Carolina—survived challenges from Trump-backed opponents in 2022, the general trend has been a consolidation of power around the former president’s preferences.

The Redistricting Battle in Indiana

In Indiana, where the primary is scheduled for May 5, Trump’s influence is being tested over a dispute regarding redistricting. In 2025, Trump pressured state Republicans to use their legislative supermajorities to redraw political boundaries to eliminate two safe Democratic seats. Despite invitations and pressure from the White House, as well as two visits from Vice President J.D. Vance, state Republicans refused.

In response to this rejection, Trump endorsed primary challengers against eight GOP state senators who voted against the redistricting measure. The campaign to replace these incumbents has seen a significant financial investment, with Trump and his allies spending $8 million on television advertisements, alongside additional millions for digital and mail campaigns targeted at the state’s older GOP base.

The conflict has split prominent Indiana Republicans. Former Governor Mike Pence has opposed Trump’s intervention, advocating for local autonomy. Speaking at an event at Harvard in 2025, Pence stated:

I would simply defer to the state legislatures and the governors to determine what they think is appropriate … whether it be in Indiana, Texas, California or anywhere else

Mike Pence

Conversely, current Governor Mike Braun previously attempted to gather Republican support for Trump’s proposed map. That plan would have granted the GOP all nine of Indiana’s U.S. House seats, despite the fact that Kamala Harris won 40% of the vote in 2024, Joe Biden won 41% in 2020, and Hillary Clinton won 38% in 2016.

The Feud with Thomas Massie in Kentucky

In Kentucky, the May 19 primary serves as a showdown between Trump and Representative Thomas Massie. The tension dates back to March 2020, when Massie blocked a COVID-19 relief spending bill to force a recorded vote on the membership’s positions. The move angered Trump, who at the time suggested the GOP should remove Massie from the party.

Despite his conservative credentials, Massie has frequently clashed with the White House, including being the sole dissent in a 2022 vote to condemn antisemitism and opposing support for Ukraine against Russia. Trump has intensified his campaign against Massie, visiting his district last year and accusing the congressman of being disloyal to the Republican Party, disloyal to the people of Kentucky, and disloyal to the United States of America.

Trump has thrown his support behind challenger Ed Gallrein, urging him to run via social media. Massie, a seven-term House Republican, has remained largely indifferent to the attacks.

The Texas Senate Runoff

Texas presents a different challenge, with a GOP runoff scheduled for May 26 between Senator John Cornyn and Attorney General Ken Paxton. Cornyn, an establishment Republican and ally of former Majority Leader Mitch McConnell, is a prolific fundraiser with deep ties to Texas oil interests.

In the initial three-way primary, Cornyn received 42% of the vote, while Paxton received 41% and Representative Wesley Hunt received 14%. While Trump has flirted with backing Paxton, institutional Republicans hope the former president remains neutral to give Cornyn the best chance of retaining the seat.

Democrats are monitoring the Republican divide closely. James Talarico has emerged as a leading fundraiser for the Democrats, raising hopes that he could become the first Democrat to win a statewide race in Texas in 30 years.

Other Key Contests: Georgia and Louisiana

In Georgia, the May 19 primary features a three-way race between Congressmen Buddy Carter and Mike Collins, and former coach Derek Dooley, who has attracted Trump’s interest. The Republican nominee will face incumbent Senator Jon Ossoff, who has raised nearly $14 million this quarter, dwarfing the combined $2 million raised by his GOP rivals. If no candidate wins a majority on May 19, a runoff will occur on June 16.

Louisiana’s May 16 primary is similarly volatile. Senator Bill Cassidy, a moderate who voted to impeach Trump during his second trial, is facing a challenge from a back-bench rival endorsed by Trump. While Cassidy recently voted to remove Robert F. Kennedy Jr. From a committee despite Kennedy’s appointment as Health and Human Services Secretary, the move did not secure Trump’s support. A runoff in Louisiana is scheduled for June 27 if no candidate secures a majority.