President-elect Donald Trump's pick to lead the U.S. Department of Defense wrote in a best-selling book that "the next commander in chief will need to clean house" at the Pentagon.

Pete Hegseth, 44, spent the last eight years on a Fox News morning show building a loyal following. In his latest book, "The War on Warriors: Behind the Betrayal of the Men Who Keep Us Free," Hegseth wrote that generals and service academy leaders advancing diversity, equity, and inclusion policies have weakened the U.S. military. He also wrote that "the next commander in chief will need to clean house."

U.S. Rep. Mike Waltz, R-Fla., the first Green Beret to serve in Congress, said Hegseth has the determination to fix problems at the Pentagon.

"The Pentagon is in need of real reform, and they're getting a leader who has the grit to make it happen," Waltz said in a post on X.