“Former generals as SecDef should be the exception not the norm,” Representative Michael Waltz, Republican of Florida and a former Army Green Beret, said in a Twitter message. He praised Ms. Flournoy as qualified on a range of pressing issues, including the defense industrial base and China, and added, “Too bad nominating the 1st female SecDef isn’t ‘diverse’ enough for #Biden and House Dems.”
Representative Elissa Slotkin, a Michigan Democrat on the House Armed Services Committee, said in a statement that she had “deep respect” for General Austin, but noted: “Choosing another recently retired general to serve in a role that is designed for a civilian just feels off. The job of secretary of defense is purpose-built to ensure civilian oversight of the military.”
Other Democrats on the Senate committee, including Senator Tammy Duckworth of Illinois, a veteran, voted against the waiver for Mr. Mattis and are expected to reject one for Mr. Biden’s nominee.
Several scholars who have studied civilian-military relations, including some who supported a waiver for Mr. Mattis, also say they oppose such a move this time.
“Mattis, like Marshall, was an emergency situation; this isn’t,” said Eliot A. Cohen, the dean of the Johns Hopkins School of Advanced International Studies and a former Pentagon official. “The law prohibiting recently serving officers from serving as secretary of defense is sound, and there are plenty of good civilian candidates. It’s a breach of civil-military norms.”
General Austin, 67, is the only African-American to have headed the military’s Central Command, the marquee combat command, with responsibility for most of the places where the United States is at war, including Iraq, Afghanistan, Yemen and Syria. Mr. Biden spent time during his years as vice president in the White House Situation Room with General Austin and had a level of personal comfort with him that he feels is essential to the role, said people familiar with his thinking.
The Congressional Black Caucus also threw its support Tuesday behind the retired general. “Black Americans have sacrificed their lives for this country in every war since the Revolutionary War,” the caucus said in a statement. “Appointing retired Gen. Lloyd Austin to a position of command and authority over the United States military, second only to the president of the United States, is historic and well deserved.”
Helene Cooper and Michael Crowley contributed reporting.