Joe Biden expected to nominate retired general Lloyd Austin for defense secretary

WASHINGTON -- President-elect Joe Biden is expected to name retired four-star Army general Lloyd Austin as his choice to lead the Defense Department, four sources familiar with Biden's plans tell ABC News.

If confirmed, Austin would be the first Black defense secretary in American history.

Austin, the former commander of US Central Command - with jurisdiction over military activities in the Middle East, retired in 2016 after more than 40 years of military service, including a stint leading U.S. forces in Iraq and the campaign against ISIS.

Austin will need a waiver from Congress to lead the Pentagon, given that he is less than seven years from active duty.

Congress granted retired Marine Corps Gen. Jim Mattis the same waiver in 2017, to allow him to serve as President Trump's first defense secretary.

Sen. Jack Reed, D-Rhode Island, the top Democrat on the Senate Armed Services Committee, expressed concern in 2017 that providing a waiver to Mattis would set a "dangerous" new precedent for leadership of the Pentagon.

"Waiving the law should happen no more than once in a generation. Therefore I will not support a waiver for future nominees," he said. "It is up to this committee to ensure that the principle of civilian control of the armed forces ... remains a defining tenet of our democracy."

Biden was under pressure from allies in the Congressional Black Caucus to put forward a Black nominee to lead the Pentagon, encouraging him to select Austin or former DHS Secretary Jeh Johnson over Michele Flournoy.

A former senior Defense Department official in the Obama administration, Flournoy, who is white, was also expected to be a frontrunner for the role in a Hillary Clinton administration.

Austin, unlike Flournoy and roughly 500 other national security figures, did not sign an open letter ahead of the election endorsing Joe Biden.