In this Sept. 16, 2015, photo, then-U.S. Central Command Commander Gen. Lloyd Austin III, testifies on Capitol Hill in Washington. Biden will nominate the retired four-star Army general to be secretary of defense, but the prospect of having another recently retired general in the position is stirring unease in Congress. Credit: Pablo Martinez Monsivais / AP

WASHINGTON — President-elect Joe Biden’s pick of Lloyd J. Austin to be secretary of defense is stirring unease in Congress, reflecting fears that putting another recently retired general in the job could further undermine the principle of civilian control of the military.

Biden’s transition team announced Tuesday afternoon that the former general would be the president-elect’s nominee. Austin would be the first Black leader of the Pentagon, and the historic nature of the nomination in a year of extraordinary racial tension in the country, adds an intriguing dimension to the debate in Congress over one of the key members of Biden’s Cabinet.

Austin was an unexpected choice. Most speculation centered on Michele Flournoy, who would have been the first woman to run the Pentagon. Austin is widely admired for his military service, which includes leading troops in combat in Iraq and Afghanistan and overseeing U.S. military operations throughout the greater Middle East as head of Central Command. 

But getting him installed as Pentagon chief will be more complicated than usual. He must win a congressional waiver of a requirement that a defense secretary be out of uniform at least seven years before taking office. Austin retired in 2016 after 41 years in the Army.

Such a congressional waiver has been granted only twice: in 1950 for George Marshall and in 2017 for James Mattis, the retired Marine general who became President Donald Trump’s first defense secretary. Among Maine’s delegation, Sens. Angus King and Susan Collins both voted in favor of the waiver for Mattis, while Rep. Chellie Pingree of the 1st District voted against it.

Members of Maine’s delegation were noncommittal on Austin’s nomination on Tuesday, though Collins and Rep. Jared Golden of the 2nd District, a Democrat and Marine veteran of the Iraq and Afghanistan wars elected in 2018, looked to be most dubious of the idea of another waiver.

Collins said in a statement that she would “need to take a hard look” at the Biden administration’s justification for a waiver for Austin, saying another waiver in such a short timespan could “compromise” the principle of civilian control.

“I supported a one-time waiver in the case of Secretary James Mattis with the belief that the circumstances at the time warranted a rare exception — not the establishment of a new precedent which erodes the basic principle of civilian control of the military,” Collins said.

Golden characterized Austin in a statement as “an outstanding example of American military leadership,” but pointed to tradition.

“I am skeptical that Congress should — for the second time in four years — erode this requirement, but the president-elect and his nominee have the right to make their case for why they believe such action is necessary,” Golden said. “I will give it serious consideration.”

A spokesperson for King, an independent who caucuses with Democrats, said the senator would review whether the nominee’s qualifications justify a waiver and whether the “fundamental principle” of civilian control would be maintained. A spokesperson for Pingree, a Democrat, said she would evaluate the waiver when it came up in the House for a vote. 

Some prominent Democrats opposed the Mattis waiver outright, and among those who voted for it, Sen. Jack Reed of Rhode Island said then that he would not support another. Civilian control of the military is rooted in Americans’ historic wariness of large standing armies with the power to overthrow the government it is intended to serve. That is why the president is the commander in chief of the armed forces, and it reflects the rationale behind the prohibition against a recently retired military officer serving as defense secretary.

Some Democrats who agreed to the 2017 waiver saw Mattis as tempering Trump’s impulsive nature and offsetting his lack of national security experience. Now the Mattis period at the Pentagon is viewed by some as an argument against waiving the seven-year rule for Austin. Mattis critics say he tended to surround himself with military officers at the expense of a broader civilian perspective. He resigned in December 2018 in protest of Trump’s policies.

Rep. Elissa Slotkin, a Michigan Democrat, said she has mixed feelings, including deep respect for Austin, with whom she worked as a Pentagon official during his years in Iraq and Afghanistan, but reservations because “the job of secretary of defense is purpose-built to ensure civilian oversight of the military.”

One of the people who confirmed Biden’s decision said the selection was about choosing the best possible person but acknowledged that pressure had built to name a candidate of color.

Biden has known Austin at least since the general’s years leading U.S. and coalition troops in Iraq while Biden was vice president. Austin was commander in Baghdad of the Multinational Corps-Iraq in 2008 when Barack Obama was elected president, and he returned to lead troops from 2010 through 2011.

This story was written by Robert Burns and Jonathan Lemire. AP writers Matthew Daly and Zeke Miller and Bangor Daily News writer Jessica Piper contributed to this report.