President-elect Donald Trump is expected to appoint Representative Michael Waltz, a Republican from Florida, as national security adviser, two sources familiar with the matter told CBS News, the BBC’s US partner.

Waltz, a veteran of the war in Afghanistan and a longtime Trump supporter, was re-elected to Congress last week — though he will have to leave office to serve in the White House.

In this role, Waltz would serve as a key adviser to the White House on national security and foreign policy matters. It is a prominent role that needs no confirmation.

Florida Sen. Marco Rubio is in talks to become Trump’s nominee for secretary of state, although the choice has not yet been finalized, two sources told CBS.

Waltz and Rubio’s offices did not respond to the BBC’s request for comment.

Waltz, a decorated Green Beret and Army veteran, served multiple tours in Afghanistan, the Middle East and Africa.

He drew on his experiences in the Pentagon during the George W. Bush administration and in combat in his book Warrior Diplomat: A Green Beret’s Battles from Washington to Afghanistan.

Waltz’s military experience led to key assignments on the National Security Committee when he was elected to Congress in 2018 and served on the Armed Services, Foreign Affairs and Intelligence committees.

The Florida congressman’s positions in Congress closely align with Republicans’ political views on national security and foreign policy since Trump’s election in 2016 — but they also recognize the U.S.’s key role in global affairs.

Waltz has suggested that NATO allies should increase their defense spending, although he has not gone as far as Trump and said the US should leave the alliance altogether.

“Look, we can be allies and friends and have difficult conversations,” Waltz said last month.

He has said the U.S. should maintain its support for Ukraine, but in recent weeks he has called for a reassessment of U.S. funds sent to help the country.

Waltz has also taken a tough stance on China during his time in Congress, arguing as chairman of the Armed Services Subcommittee on Readiness that the U.S. must do more to prepare for conflict in the Pacific.

Since the US withdrawal from Afghanistan in 2021, Waltz has regularly criticized President Joe Biden and the White House for their decision to leave the country.

Waltz would be the second member of Congress called up to serve in the next Trump administration, which will require him to resign from office in the House of Representatives and potentially reduce Republicans’ controlling majority.

He would be the fifth national security adviser to serve under Trump, who appointed four different men to the position during his first term. He fired three.

Michael Flynn, a retired general and Trump loyalist, lasted just 24 days before being fired.

Trump appointed and then fired H.R. McMaster, another retired general who would later criticize the president-elect and his allies in a memoir he published earlier this year.

John Bolton, who served in the post for 17 months and was Trump’s longest-serving national security adviser before he was also fired, became highly critical of his former boss and argued against the newly elected president’s efforts to return to the White House.

Robert O’Brien, a lawyer who served in the Bush administration, has completed Trump’s first term as national security adviser.

It is not yet certain that Rubio will be nominated as secretary of state, but the Florida Republican’s career has made him America’s next top diplomat.

Several US media outlets have reported that Rubio is in discussions with the Trump transition team about the senior position, but that these have not yet been finalized. It appears the president-elect could still change his mind.

Rubio, however, built his resume in the Senate.

He is vice chairman of the Senate Intelligence Committee and a member of the Foreign Relations Committee.

Rubio is considered a foreign policy hawk, especially toward China and Iran. While supporting Ukraine, he previously said the ongoing conflict between Russia and Ukraine “must be brought to an end.”

Trump and Rubio now have a cordial relationship, but it wasn’t always that way.

Both men ran for president in 2016, and the two developed a bitter rivalry. They clashed over a variety of issues — most notably immigration — and the conflict led to several insults, with Trump calling the senator “Little Marco” and Rubio mocking Trump’s “little hands.”

The Florida senator, 53, supported his rival and the two mended their relationship during Trump’s first term.

Rubio was one of the earliest supporters of Trump during this election’s primaries.

Rubio, the son of working-class Cuban immigrants, was first elected to the Senate in 2010.

He has since become a mainstay of Republican politics and was once suggested as a potential running mate for 2012 Republican nominee Mitt Romney and for Trump in 2024.