Two Florida lawmakers known for their tough stances towards China are in the running for senior foreign relations jobs in the administration of President-elect Donald Trump, US media reports say.

Senator Marco Rubio, who challenged Trump for the 2016 presidential nomination, is in talks to be his future secretary of state, two sources told the BBC’s US partner, CBS News. But his appointment has not yet been agreed.

And Michael Waltz, a congressman and military veteran, could play his own significant role in Trump’s new government. He is favourite for the national security adviser, two sources familiar told CBS.

Rubio and Waltz’s offices have not responded to the BBC’s request for comment.

Trump’s administration is starting to take shape after his win in last week’s presidential election.

His Republican Party is closing in on full control of Congress. They have won back control of the Senate, the upper chamber, and they are inching towards a majority in the House, the lower chamber, as vote-counting continues.

Some of the appointments – including secretary of state – will require senators’ approval, although Trump has demanded that the next Senate leader let him bypass this. He can give out other jobs – like national security adviser – directly.

The reported roles for Rubio and Waltz come after Trump made Susie Wiles his chief of staff, named former immigration official Tom Homan as his “border tsar” and nominated New York Congresswoman Elise Stefanik as his future ambassador to the United Nations.

A president-elect has responsibility for about 4,000 political appointments. During his first presidency, it took Trump months to assemble his cabinet.

It is not yet certain that Rubio, 53, will be nominated to serve as secretary of state – a role that functions as America’s top diplomat – but the Florida Republican’s career has set him up to take the role.

Several US media outlets have reported that Rubio is in talks with the Trump transition team over the senior position, but it has not been finalised. It appears the president-elect could still change his mind.

Rubio serves as the vice-chairman of the Senate Intelligence Committee and sits on the Foreign Relations Committee.

He is considered a foreign policy “hawk” – meaning someone who takes hard-line positions – towards Iran as well as China.

While supportive of Ukraine, he previously said the country’s war with Russia needed to “be brought to a conclusion”.

Rubio and Trump were opponents in the race for the Republican presidential nomination in 2016 and the two developed a bitter rivalry.

They clashed on a variety of issues – particularly immigration – and the conflict led to various insults. Trump referred to the senator as “little Marco” and Rubio mocked Trump’s “small hands”.

But Rubio went on to endorse his rival and campaigned for him ahead of the 2024 election. He was also in the frame to be Trump’s running mate – a role that ultimately went to JD Vance, who takes a similar view towards China.

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

Waltz, 50, a military veteran and a long-time Trump supporter, was re-elected to Congress last week.

Two sources have confirmed to CBS that he is expected to be named national security adviser – which would involve identifying and countering threats to the US. The appointment would not require Senate approval.

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

In his book, Warrior Diplomat: A Green Beret’s Battles from Washington to Afghanistan, he documented his experiences serving in the Pentagon during the George W Bush administration and in combat operations overseas.

Like Rubio, Waltz has taken a tough line on China. As chair of the Armed Services Subcommittee on Readiness, he argued the US needed to do more to prepare for conflict in the Pacific.

He has also said the US should maintain its support for Ukraine, but in recent weeks has advocated for a reassessment of US spending on aid for the war effort.

Waltz has said Nato allies should increase their defence spending, though he has not gone as far as Trump – who has reportedly suggested the US could leave the Western military alliance, to which it is the main contributor.

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

Since the 2021 withdrawal from Afghanistan, Waltz has frequently criticised President Joe Biden and the White House.

He would be the second member of Congress to be asked to serve in the next Trump administration, which would require him to resign his office in the House of Representatives.

That could have ramifications if the Republicans end up controlling the House with a slim majority. Waltz’s resignation would cut any majority by one until a replacement could be elected.

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

Trump sacked three of them: Michael Flynn, HR McMaster and John Bolton. The latter of the three actively campaigned against Trump in the 2024 election.

North America correspondent Anthony Zurcher makes sense of the race for the White House in his twice-weekly US Election Unspun newsletter. Readers in the UK can sign up here. Those outside the UK can sign up here.