President Trump’s new pick for national security adviser may be subject to an unusual Senate confirmation hearing if he wants to keep his military rank while serving in the job.

Lt. Gen. H.R. McMaster was chosen by Trump this week to replace ousted national security adviser Michael T. Flynn, who was dispatched from the job because he misled Vice President Pence about what he told a Russian official regarding sanctions on that country before the inauguration.

The national security adviser does not have to be confirmed by lawmakers. But the Senate will have to agree to McMaster retaining his three-star general rank as he moves into a new job. In the past, generals seeking to retain their stars when moving to a new position have been confirmed by the Senate without a public hearing.

Senators may agitate for an opportunity to let the committee grill McMaster, given the controversy surrounding Flynn’s departure and allegations from the intelligence community that Russia intervened in the U.S. elections to help Trump win.

McMaster could choose to drop a star from his rank to proceed more smoothly to the post, and the Trump administration has not yet formally recommended that he retain his third star in the new position.

White House spokesman Sean Spicer said this week that McMaster will continue to be on active duty while serving as national security adviser.

Although the Senate Armed Services Committee can hold a hearing on McMaster’s rank, Chairman John McCain (R-Ariz.) has not said whether he will do so.

McCain has expressed general confidence in Trump’s national security team but raised concerns about Flynn’s comments to Pence about his contacts with Russian ambassador to the United States Sergey Kislyak.

Any hearing on McMaster could give Democrats and Trump critics a chance to shine a light on allegations that the Trump team had contact with Russian officials during the campaign and that Russia intervened in the 2016 election, according to intelligence officials.

Both Democrats and Republicans have embraced McMaster’s selection, generally praising the highly decorated officer and the roles he played in the Gulf War and the Iraq and Afghanistan conflicts. McMaster generally takes a hard line on relations with Russia.

McMaster is also the latest in a line of generals that Trump has tapped to fill his national security team — a pattern that makes some in Congress uneasy.

“There are weighty questions about senior active duty officers and non-military service that deserve careful consideration,” Senate Armed Services Committee ranking Democrat Jack Reed (R.I.) said in a statement Wednesday.

Last month, senators raised similar concerns about retired Gen. James Mattis’s selection as secretary of defense. Mattis needed a waiver from Congress because he had not retired from active service for the requisite seven years. Despite those concerns, the Senate voted overwhelmingly to confirm him.

The same will likely be true for a Senate vote to confirm McMaster’s third star, if he and the White House submit a bid to keep it.

The White House has pointed to one precedent indicating they don’t expect McMaster to take a military demotion: Former Secretary of State Colin Powell, who served as national security adviser to former president Ronald Reagan.

When Powell got that job in 1987, he was still on active duty as a three-star general, and needed to have his third star approved by the Senate — an episode he wrote about briefly in his autobiography.

Powell did not immediately return a request for comment about whether he had been subjected to a public confirmation hearing as part of that process, and Armed Services Committee staff could not say with full certainty that his third star had been approved without an appearance before the panel. There is no readily available transcript of any public hearing having taken place.

Karen DeYoung contributed to this report.