Rep. Thomas Massie (R-KY) will face challenger Ed Gallrein in Tuesday’s Republican primary, but the incumbent is really locking horns with President Donald Trump.Trump’s endorsement of Gallrein and decision to deploy his political operation against Massie is what has made this a competitive primary, in addition to an expensive, nasty, and intensely personal one.Unlike many Republicans who have raised Trump’s ire in the past, Massie can plausibly argue that on a number of issues — Jeffrey Epstein files transparency, no more foreign wars, fighting government surveillance and the “deep state” — he is a MAGA candidate.

But Massie has clashed with Trump since a fight over COVID-19 emergency spending in his first term, and the feud deepened when the libertarian-leaning Kentucky lawmaker partnered with Rep. Ro Khanna (D-CA) on legislation to force the release of the Epstein files.

Since former Republican Georgia Rep. Marjorie Taylor Greene resigned from Congress rather than run for reelection after breaking with Trump, Massie’s primary will be the biggest test of whether MAGA is about a set of policies versus trusting Trump, a populist ideological movement rather than a cult of personality dominated by one man who will soon be term-limited out of office.