WASHINGTON (AP) — Republican Rep. Chip Roy, an outspoken fiscal conservative known for his willingness to challenge party leadership, announced Thursday that he is running for Texas attorney general.

Now in his fourth term, Roy is a prominent member of the House Freedom Caucus, a hard-line conservative faction that wields outsize influence in the narrowly divided House. He was a central player this summer in the negotiations around President Donald Trump’s big tax bill. But the lawmaker’s relationship with Trump has been complicated at times as one of the few Republicans who initially pushed back against Trump’s claims that the 2020 election was stolen.

Roy enters an increasingly crowded Republican primary field to succeed Attorney General Ken Paxton, who is challenging Sen. John Cornyn in the Republican primary next year.

“Texas is under assault — from open-border politicians, radical leftists, and faceless foreign corporations that threaten our sovereignty, safety, and our way of life,” Roy said in a statement. “It’s time to draw a line in the sand.”

Roy served as Paxton’s second-in-command in the attorney general’s office before winning election in 2018. Roy was the most prominent member of his party to call for Paxton to resign in 2020 after the attorney general’s top deputies reported him to law enforcement for alleged crimes including bribery and abuse of office.