WASHINGTON — President-elect Joe Biden's nomination of Lloyd Austin has set up a tough question for Congress: confirm the first Black secretary of defense or reinforce a 73-year-old law designed to keep recently retired military officers from running the Pentagon.

Austin, 67, a four-star general, led the U.S. Central Command before retiring in 2016. He needs a waiver from a 1947 law that sought to bolster civilian control of the military by requiring a seven-year cooling-off period for officers after relief from active duty.

Lawmakers are divided on whether to grant it.

“I understand the importance of civilian control. I have some concerns about being asked to do a waiver,” Sen. Mazie Hirono, D-Hawaii, who sits on the Armed Services Committee that will oversee the nomination, said. “So I will be taking those into consideration.”

Unlike the process of confirming nominees which is done by just the Senate, this type of exemption must be approved by both chambers. Just two Pentagon nominees have received waivers since the requirement was enacted after World War II: Harry Truman's pick of George Marshall in 1950, and President Donald Trump's choice of James Mattis in 2017.

During the Trump administration, there was concern that policy decisions historically made by civilians have been left to military brass. And that is driving a desire by some to see another civilian take over when Biden becomes president