Republican senators expressed disappointment Thursday over reports that national security adviser Mike Waltz would be stepping down from his post after he became embroiled in a controversy over inadvertently sharing sensitive information with a reporter on Signal, a commercial app.

Several hours after those reports surfaced, President Trump announced he would nominate Waltz to serve as ambassador to the United Nations.

Prior to the announcement on Truth Social, GOP senators had expressed dismay that Waltz would no longer be national security adviser.

“He did a very good job as national security adviser. It’s the prerogative of the president to decide who his team will be, but I was sorry to see that news,” Sen. Ted Cruz (R-Texas) said.

Sen. Mike Rounds (R-S.D.) said Waltz’s departure is “a pretty significant modification” and “a pretty significant change” to President Trump’s national security team.

Sen. Thom Tillis (R-N.C.) wasn’t happy to hear about Waltz’s sudden departure as national security adviser

“Disappointing, he’s a good guy,” he said.

Senate Armed Services Committee Chair Roger Wicker (R-Miss.) said he wanted to learn more about the circumstances of Waltz’s resignation before commenting on the matter.

“I’m not going to react because I heard it during the hearing, I don’t know any context,” he said.

Many Republican senators thought Waltz was a good fit for the job, with one GOP lawmaker telling The Hill “he had a very good background.”

Waltz graduated from the Virginia Military Institute and later served as a special forces officer and was awarded four Bronze Stars.

Waltz, a former member of the House, served on the China Task Force during his career in Congress and is viewed as a China hawk.

Sen. John Cornyn (R-Texas), who views China “as the biggest challenge we have,” said he hopes Trump will appoint someone with similar views to replace Waltz.

But he acknowledged the national security adviser serves at the pleasure of the president.

“There’s one guy whose opinion matters most and that’s the president of the United States and I think all those folks serve at the pleasure of the president, which means you may not be there as long as you thought you would,” he said.

Updated at 3:15 p.m.