Retiring Republican Sen. Thom Tillis says in a new book that his 2025 vote to confirm Pete Hegseth as Defense secretary is the “biggest regret of my career.” 

The 66-year-old Tillis began his political career in 2002 when he was elected to the park board for the town of Cornelius, North Carolina. He was elected to the Senate in 2014. Tillis, who has clashed with President Donald Trump, announced in June that he would not seek a third term.

His Hegseth confirmation vote brought the 100-member Senate total to 50-50, resulting in Vice President JD Vance having to cast the decisive, tie-breaking vote.

Tillis writes about his vote for Hegseth – whose confirmation process was confound by allegations about his management style, treatment of women and excessive drinking – in his book “How to Lose Friends and Antagonize Presidents,” to be published Tuesday and reviewed by the Associated Press.

“I know for a fact that there are others like me,” Tillis writes. “Republicans who agreed to go along with the early demands of the Trump team no matter how ridiculous they were, believing that failing to do so would mean the end of their political career, and who now see that things have gone way too far."