Retired Gen. Lloyd Austin is President-elect Joe Biden’s pick for defense secretary, the top civilian post at the Pentagon. Nominating a recently retired military officer will require a waiver from Congress, which some key lawmakers oppose.

Commander of US Central Command Gen. Lloyd Austin III conducts a media briefing on Operation Inherent Resolve, the international military effort against (IS) Islamic State group, on October 17, 2014, at the Pentagon in Washingon, DC. Confronting the Islamic State group in Iraq is the top priority for the US-led coalition fighting the jihadists, while air strikes in Syria are meant to disrupt the group’s supply lines, the US commander overseeing the air war said Friday. AFP Photo/Paul J. Richards (Photo credit should read PAUL J. RICHARDS/AFP via Getty Images)