The procedural wrinkle was first reported Tuesday afternoon by Defense News.
At Tuesday’s press briefing, White House press secretary Sean Spicer said McMaster will stay on active duty. But when asked whether that requires him to be confirmed, Spicer said “no,” without elaboration.
There is precedent for an active-duty military member to serve as national security adviser.
Colin Powell was a lieutenant general when he was appointed national security adviser in 1987 and retained his rank after a Senate vote. Brent Scowcroft had that rank when he was appointed to the job in November 1975, but retired from active duty a month later.
Arnold Punaro, a former staff director of the Senate Armed Services Committee when Powell was appointed, said the committee back then followed the normal procedures for confirming a three-star for Powell. He said he would expect the committee to do the same for McMaster.
The normal procedure to become a three-star official is for that person to fill out a questionnaire, but they are not required to testify before the Senate Armed Services Committee.
The Senate routinely confirms military appointments in a large tranche. For example, last December the Senate approved dozens of military nominations by unanimous consent.
One wrinkle is that the questionnaire both then and now asks the nominee whether he or she will agree to testify in the future, and national security advisers typically are not expected to testify before Congress. Punaro could not recall whether the committee took the question off for Powell and would not speculate on whether it might for McMaster.
In 1987, Punaro said, there was also some back and forth between the White House counsel and the committee because then-Chairman Sam Nunn (D-Ga.) had some concerns about whether active-duty military should serve in the White House.
Punaro stressed the vote on McMaster will be solely about his rank.
“The Senate is required to confirm him as a three-star, not as national security adviser,” he said. “It will not be about that position. It will be about his rank.”
McMaster was announced as Trump's pick for national security adviser on Monday, replacing Michael Flynn, who was ousted last week following allegations that he misled Vice President Pence and other White House officials about his conversations with Russia's ambassador to the U.S.