Ivan Cholakov/iStockBy LUIS MARTINEZ, ABC News

(WASHINGTON) — As a recently retired military general is Lloyd Austin the right pick to run the Defense Department under a Biden administration? Will the need for a congressional waiver so he can take the job threaten the concept of civilian control of the military?

Those are the questions being asked as President-elect Joe Biden announced that he will nominate the retired Army general to be his defense secretary.

In order for Austin to serve as Defense Secretary he will require a waiver from both houses of Congress, just as retired Marine Gen. James Mattis did four years ago under the Trump administration.

The waiver is needed because Austin retired from the Army four years ago, which is less than the seven-year gap any nominee to be a secretary of defense must have from the end of their military service. If approved, Austin would only be the third to receive the waiver to take the position, but the second in four years.

On Wednesday, both Biden and Austin sought to reassure any concerns that a waiver for Austin might erode civilian control of the military.

“There’s a good reason for this law, that I fully understand and respect,” Biden said on Wednesday as he announced Austin as his pick to run the Pentagon. “And I would not be asking for this exception if I did not believe this moment in our history didn’t call for it.”

In his remarks, Austin said, “I come to this new role as a civilian leader with military experience, to be sure, but also with a deep appreciation and reverence for the prevailing wisdom of civilian control of our military.”

“I look forward to surrounding myself with experienced, capable civilian appointees and career civil servants who will enable healthy, civil military relations grounded in meaningful civilian oversight,” he added.

However, some Democratic lawmakers have expressed concerns that they will be asked to once again consider a waiver just four years after they voted to do so for Mattis. Being asked to give Austin the waiver places the 17 Democratic senators and 150 Democratic House Representatives who voted against the Mattis waiver in an awkward position.

Do they now adjust their principled opposition from four years ago only because Austin has been nominated by a Democratic president-elect?

Contacted by ABC News on Wednesday, three of the 17 Democrats in the Senate who voted against giving Mattis a waiver in 2017 said they plan to oppose a waiver for Austin, though they could end up voting to confirm him.

“I will not support the waiver,” Sen. Richard Blumenthal, D-Conn., told reporters on Tuesday.

“I believe that a waiver of the seven-year rule would contravene the basic principle that there should be civilian control over a nonpolitical military,” he said. “The principle is essential to our democracy.”

Sen. Jack Reed of Rhode Island, the top Democrat on the Senate Armed Services Committee, said in 2017 that his vote granting Mattis a waiver was a one-time event. But on Tuesday, Reed allowed himself some wiggle room and said he would “carefully review” Austin’s nomination.

“It is the obligation of the Senate to thoroughly review this nomination in the historic context it is being presented and the impact it will have on future generations,” said Reed. “Indeed, one cannot separate the waiver from the individual who has been nominated.”

Austin received some high-powered support from former Defense Secretary Robert Gates who in a statement provided to ABC News said he “will be a superb Secretary of Defense.”

“He is an extraordinary leader with a deep understanding of the international challenges facing the United States and the Defense Department. From personal experience, I know him to be a person of unshakeable integrity, independent of thought and conscience, and a steady hand,” Gates said.

And former Secretary of State Colin Powell, also a retired general, called Biden’s choice “superb.”

“General Austin has served splendidly at all combat and civilian levels in the Armed Forces. He has demonstrated his warfighting skills and his bureaucratic, diplomatic and political acumen,”Powell wrote on Facebook. “Being older than him, I watched him closely and served as a mentor. Congress should have no concern in waiving the requirement that he serve at least seven years in civilian life after retiring before accepting the Secretary of Defense position. His civilian business experience in retirement expands his capability to manage the Defense Department. He knows troops and they know and respect him. They will be a great team.”

But national security analysts questioned whether Austin is a right fit for the job as he passed over civilians with significant Pentagon experience like Michele Flournoy and Jeh Johnson.

“Is the nation so short on leadership and those with national security experience that the only person the new administration could find is a recently retired senior general?” said retired Col. Steve Ganyard, a former deputy assistant secretary of state and now an ABC News contributor.

“Civilian control of the military is a fundamental tenet of the Constitution,” said Ganyard. “It’s important that civilian control of violence be both perception and reality. Only authoritarian countries don’t separate their militaries from civilian control.”

“I do have some concerns, but the doom and gloom expressed by many about the general, the biggest being his potential (mis)handling or even downright abuse of civil-military relations in the Department of Defense, is unwarranted,” Bilal Y. Saab a senior fellow for the Middle East Institute wrote in an essay.

“Just because you’re a general doesn’t mean you’re going to blow up civilian control of the military, and just because you’re a civilian doesn’t mean you’re automatically going to properly enforce that civilian control,” wrote Saab.

Two retired military officials noted that Austin’s military experience will be invaluable for when to make the argument not to use military force.

“I believe military members, especially those that served in combat, are more aware of the consequences of those decisions,” said one official.

Two decades of constant operations means most officers who rise to the rank of general have experienced combat or made decisions about whether to engage in combat over the past two decades.

“Based on their personal experiences they will most likely be less prone to leaning toward war as a solution,” said the official.

But if a military option is the only option left, this official speculated that the experience of extended protracted wars could mean a recently retired military officer would support an all-out effort to ensure a quick victory instead of “a low investment prolonged struggle.”

The first time that Congress granted a waiver to a recently retired military officer to serve as defense secretary was in 1950 when former Army general and Secretary of State George Marshall was nominated as defense secretary.

A waiver granted just three years after the enactment of the National Security Act of 1947 that included the seven year gap from the end of military service to ensure civilian control of the military.

ABC News’ Benjamin Siegel contributed to this report.

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