Defense Secretary Pete Hegseth on Monday traveled to Kentucky to campaign against Rep. Thomas Massie on the eve of the Kentucky primary, stepping away from the Iran war to wade into a congressional election testing President Donald Trump’s political clout. Hegseth delivered remarks designed to undermine Massie, one of Trump’s chief Republican critics in Congress, and to praise Massie’s rival, former Navy SEAL Ed Gallrein.

Hegseth said he was speaking “as a private citizen” and not as a member of Trump’s Cabinet, according to the Associated Press. Yet he referenced Trump repeatedly as he called on voters to send Trump a “reinforcement” in Congress.

“President Trump needs reinforcements, and that’s what war fighters do. They stand behind leaders and have their back,” Hegseth said. “Too often, Thomas Massie has acted like his job is to stand apart from the movement that President Trump leads, instead of strengthening it. When President Trump needs backup, Massie wants to debate process.”

Massie, who has represented Kentucky’s 4th Congressional District since 2012, has been a frequent target of Trump’s ire. The congressman has broken with Trump on issues including foreign policy, spending, and the Iran war. Trump has posted about Massie at least 11 times in two days ahead of the Tuesday primary, Forbes reported, endorsing Gallrein as the candidate who will “always put America First.”

The race has become a test of Trump’s ability to punish Republican lawmakers who oppose him. Massie has argued that his independent streak reflects the values of his district and has bet that Kentucky Republicans will stick with him despite Trump’s opposition.