With the Senate set to vote on the Trump administration’s latest nominee for Pentagon chief midday Tuesday, current Army Secretary Mark Esper is on track to assume the Defense Department’s top job come evening.

Following confirmation, Esper will officially be in the job as soon as President Trump signs his appointment letter, Pentagon spokesman Jonathan Hoffman told reporters Tuesday. Swearing in is set for early evening.

“Planning for a ceremonial swearing-in is ongoing,” Hoffman said.

Esper and Warren spar at confirmation hearing

Ahead of his expected confirmation as Secretary of Defense, Mark Esper sparred with Senator Elizabeth Warren over his past background in the defense industry.

Esper’s confirmation ends eight months of uncertainty at DoD, following the late December departure of then-Defense Secretary James Mattis, a near-universally admired former Marine Corps four-star general and national security scholar.

His deputy, Patrick Shanahan, had been slated to take over this summer, but allegations of domestic abuse made in his 2011 divorce filings scuttled his nomination as he prepared for a Senate Armed Services Committee hearing.

Esper, who has lead the Army department since late 2017, stepped in as acting SECDEF for three weeks leading up to his own confirmation hearing. Navy Secretary Richard Spencer has been serving as the acting Pentagon chief since July 15, as federal law prohibits officials from serving in an acting role while also being nominated for it.

Esper has received praise from both sides of the aisle, though he went head-to-head with Sen. Elizabeth Warren, D-Massachusetts, during his July 16 confirmation hearing.

Prior to returning to public service as Army secretary, Esper worked as a lobbyist for defense contractor Raytheon.

"This smacks of corruption, plain and simple,” Warren said. “Will you commit that during your time as defense secretary that you will not seek any waiver that will allow you to participate in matters that affect Raytheon’s financial interests?”

Though Esper signed an ethics statement pledging to recuse himself from deals involving the company, he is still owed about a $1 million in compensation from the company. He said he would retain his legal option to get involved in a deal, on the advice of the Pentagon’s lawyers.

Esper, a retired Army infantry lieutenant colonel, will more than likely be joined by current Army Chief of Staff Mark Milley this fall, when the Senate confirms his nomination to succeed Marine Gen. Joseph Dunford as chairman of the Joint Chiefs of Staff. A date for that vote has not been announced.

Next moves

Esper’s move to the top spot comes the same day as the expected nomination of David Norquist, who has been acting deputy defense secretary, to the Pentagon’s no. 2 role, Hoffman said.

The Pentagon’s plan for Norquist to step aside from his acting position and return to his previous job as DoD comptroller, while Spencer covers for him until his official appointment. A vote on Norquist could happen as early as next week.

“If confirmed, one of the very first things that Dr. Esper will do as secretary of defense is delegate all duties of the deputy secretary of defense to Secretary of the Navy Richard V. Spencer, who has been acting secretary of defense since July 15,” Hoffman said.

Spencer, as acting SECDEF, traveled to the U.S.-Mexico border on Friday to visit with troops deployed there as part of President Trump’s declared national immigration emergency.

He will next attend the U.S. Africa Command change of command ceremony this Friday in Stuttgart, Germany, Hoffman said.