The secretary of defense has ordered a 60-day stand down for military officials to investigate far-right extremism and racism within the ranks.
"Each of these individuals possesses unique and relevant experience, in and out of government, that I know will inform this important effort," Defense Secretary Lloyd Austin said in a Friday statement.
The Missouri Republican has voted "nay" for all six of Biden's Cabinet nominees who have come up for a Senate confirmation vote.
All Pentagon advisory board members were removed as Biden Defense Secretary Lloyd Austin cleans house of all previous administration appointees.
Former president Donald Trump had previously banned transgender people from serving in the U.S. military.
"Now more than ever, we need an experienced, competent, organized, and respected Secretary of Defense," the officials said.
Eleven of Biden's Cabinet appointments served in the Obama administration and three also served in the Clinton administration.
Democrats expressed misgivings about starting a tradition of confirming a defense secretary who is a recently retired service member, as the top Pentagon post is intended for a civilian.
Austin is accused of telling President Barack Obama that ISIS was merely a "flash in the pan."
The rule about the waiver was established over fears that a former general might be too familiar with soldiers still in active duty.