Ed Gallrein (R) defeated incumbent Rep. Thomas Massie (R) in the Republican primary for Kentucky's 4th Congressional District on May 19, 2026. Massie was the second member of the U.S. House of Representatives to lose re-election in a primary in the 2026 election cycle.

At the time of the election, this race was the only U.S. House primary in which President Donald Trump (R) endorsed a challenger to a Republican incumbent. After Massie said he would vote against the short-term government funding bill in March 2025, Trump posted on Truth Social that “HE SHOULD BE PRIMARIED, and I will lead the charge against him."

In response, Massie posted on X, “Someone thinks they can control my voting card by threatening my re-election. Guess what? Doesn’t work on me. Three times I’ve had a challenger who tried to be more MAGA than me. None busted 25% because my constituents prefer transparency and principles over blind allegiance.” Trump endorsed Gallrein on Oct. 17, 2025.

According to the University of Kentucky's Stephen Voss, "A lot of Republican voters in Massie's district are going to be willing to consider an alternative to Massie because of Donald Trump's spats with Massie. But just because you're not fully happy with your member of Congress doesn't mean you end up willing to vote for someone else.”

Massie was first elected to represent Kentucky's 4th Congressional District in a 2012 special election. He previously served as the Lewis County Judge Executive from 2010 to 2012. Massie's professional experience included working as a farmer and business owner.

Massie said, "Fourth district voters appreciate having an independent conservative voice who works for them, and I look forward to continuing my fight for transparency, constitutional rights, secure borders, a true America-first foreign policy, and fiscal responsibility.”

Gallrein was, at the time of the election, a farmer and business owner. He also served in the U.S. Navy from 1984 to 2014. In 2024, Gallrein ran to represent District 7 in the Kentucky Senate. He lost to Aaron Reed 39.3% to 38.3% in the Republican primary.

Gallrein said, "This district is Trump Country. The president doesn't need obstacles in Congress — he needs backup. I'll defeat Thomas Massie, stand shoulder to shoulder with President Trump, and deliver the America First results Kentuckians voted for.”

As of May 19, 2026, The Cook Political Report with Amy Walter and Inside Elections with Nathan L. Gonzales rated the general election as Solid Republican. Larry J. Sabato's Crystal Ball rated the general election as Safe Republican.