Sen. Elizabeth Warren (D-MA) outlined concerns about President-elect Donald Trump’s defense secretary nominee, Pete Hegseth, ahead of what is poised to be one of the fiercest confirmation battles.

In a 33-page letter, Warren demanded detailed answers to concerns over past rhetoric and allegations, including alleged personal misconduct and positions the Democrats believe could jeopardize national security. While the letter opened with congratulations for Hegseth on his nomination and expressed “serious concerns” about his qualifications, it closed by seemingly dismissing any possibility of his approval.