WASHINGTON ― U.S. President-elect Joe Biden’s first defense secretary may turn out to be President Donald Trump’s last deputy defense secretary, at least for several days.

Biden and his transition team are pushing for his national security picks to be swiftly confirmed in the wake of the attack on the U.S. Capitol last week. But Pentagon watchers say an extended confirmation process in Congress for Biden’s choice to lead the Pentagon could mean current Deputy Defense Secretary David Norquist will be asked to fill in temporarily.

There’s a potential delay because Biden’s nominee, retired Army Gen. Lloyd Austin, needs a congressional waiver from a law that bars recently retired active-duty officers from serving in the top Pentagon job. The House Armed Services Committee isn’t set to hold a hearing on the waiver until the day after Biden is sworn in, and no floor vote on the waiver has been set.

That raises the question: With the nation in the midst of a rocky transition of power, and Biden’s Inauguration less than a week away, who will run the Pentagon?

Under Title 10 (the federal law governing the armed forces), a confirmed deputy secretary automatically assumes the duties, responsibilities and authorities of the defense secretary during a defense secretary’s absence. Alternatively, Biden could ask current Army Secretary Ryan McCarthy or acting Comptroller Thomas Harker to stay on ― or ask the Senate to quickly confirm his nominee for deputy, Kathleen Hicks, and let her serve as acting secretary.

Norquist has working relationships with the combatant commanders, service chiefs and leaders of the Joint Chiefs of Staff. Still, it’s unclear how comfortable Biden and his team would be with a Trump-appointed figure running the Pentagon, even for a few days, though they may have few options.

Both Norquist and the Biden transition team declined to comment for this story.

Before he stepped into the Pentagon’s No. 2 job two years ago, Norquist became known for shepherding the Department of Defense through its first audit as the department’s comptroller, but he has made headlines for championing data analytics at the Pentagon and defending the DoD’s spectrum from disruptions by the telecom firm Ligado. While not overtly political, Norquist helped execute and defend Trump’s controversial diversion of military funds to his border wall project.

“The good government answer is Norquist,” said Arnold Punaro, a retired two-star Marine general and former staff director of the Senate Armed Services Committee. “He is someone who would faithfully discharge the duties of the office in accordance with the priorities and direction of President Biden.

“He is really the one that makes the most sense. I have been a public advocate of that approach, as we should always try to follow Title 10. And also, he is No. 1 in [Trump’s recent] executive order for succession.”

Though Politico has reported an effort’s afoot to fast-track Austin’s waiver in the House so that he can be quickly installed, the House Armed Services Committee hasn’t adjusted its schedule and wasn’t on track to do so Wednesday. Committee Chairman Adam Smith’s plan has been to first organize his panel for the new Congress, and then have Austin testify Jan. 21 on the waiver.

The Senate Armed Services Committee is scheduled host Austin for his confirmation hearing on Jan. 19. If all goes smoothly, with Republicans cooperating, Democrats could theoretically avoid or overcome filibusters and have the waiver and confirmation done by Jan. 20. But if not, Austin could be in limbo for as many as 10 days while an interim leader runs the Pentagon.

“Frankly, the House and Senate should have the waiver and his confirmation as the highest priority and should set their schedules to have this done on Jan. 20,” Punaro said.

President Barack Obama held over President George W. Bush’s defense secretary, Robert Gates; and Trump, for six months, held over Obama’s deputy defense secretary, Bob Work, among others. In each of those cases, however, there was no immediate replacement waiting in the wings.

Calling Norquist a “traditional and prudent” choice for Biden’s interim secretary, Pete Giambastiani, a former Pentagon legislative affairs official in the Trump administration, speculated Biden’s team hasn’t revealed its plans on the matter for tactical reasons.

“Perhaps the incoming Biden administration doesn’t want to give anybody any wiggle room by identifying acting defense and homeland security secretaries ― to put the pressure on Congress to confirm his people as soon as possible,” Giambastiani said.

Biden, his team, surrogates and allies have indeed called for his nominees to be quickly confirmed. On Wednesday, Biden grouped confirmations to lead the Pentagon and other agencies with the other pressing business for America like fixing the economy and the government’s coronavirus vaccine distribution plans.

“Too many of our fellow Americans have suffered for too long over the past year to delay this urgent work,” Biden said in a statement Wednesday.

Aaron Mehta in Washington contributed to this report.