it has to do with foreign money (record amounts) interfering with elections.
Trump did not originally endorse or support Thomas Massie because Massie repeatedly defied him on major legislative priorities, starting with a high-profile clash in 2020. 
Key 2020 Conflict
During the early COVID-19 pandemic, Trump pushed a massive ~$2 trillion coronavirus relief package. Massie, a libertarian-leaning Republican known for fiscal conservatism and procedural stands, tried to force a recorded vote on it (opposing a voice vote), arguing it was rushed, insufficiently conservative, and included unrelated spending. 
Trump responded aggressively on Twitter (now X):
• Called Massie a “third rate Grandstander.”
• Labeled him “a disaster for America, and for the Great State of Kentucky!”
• Urged Republicans to “throw Massie out of Republican Party!” and focus on winning the House. 
This was a rare public attack on a sitting GOP member from a sitting president. Many other Republicans also criticized Massie at the time. Massie still won his primary overwhelmingly (by ~76 points) despite the backlash. 
Later Developments (Not “From the Beginning”)
• 2022: Trump reversed course and endorsed Massie for re-election, calling him a “Conservative Warrior” and “first-rate Defender of the Constitution.” This came after Massie had survived and as Trump focused on broader party unity post-presidency.

• 2024: Massie endorsed Trump relatively late (October), after initially holding back and expressing reservations about some Trump-aligned candidates or issues.

• 2025–2026: Relations soured again. Massie opposed Trump’s signature tax-and-spending bill (“One Big Beautiful Bill Act”), pushed for release of Jeffrey Epstein files, and criticized certain foreign policy/military actions. Trump recruited and fully endorsed a primary challenger (Ed Gallrein, a former Navy SEAL), called Massie names like “weak,” “RINO,” and “the worst,” and rallied against him in Kentucky. This has turned into one of the most expensive House primaries ever, with heavy outside spending. 
