Trump, who rhetorically at least has long broken with the historic bipartisan consensus in Washington for an assertive US global role, tapped two Florida politicians who still believe in traditional US engagement with the world.

But Rubio, a senator said to be tapped for secretary of state, and Waltz, a congressman named national security advisor, differ sharply from President Joe Biden's vision of internationalism.

Rubio in a speech last year said that the United States was already in a broad global conflict with China, which "doesn't just seek to be the most powerful nation in the world, they seek to reorient the world."

The Biden administration also described China as the top long-term adversary of the United States and ramped up sanctions, but tensions have markedly eased recently, with Biden's top diplomat Antony Blinken focusing on dialogue to prevent unintentional conflict.

The Biden administration believed the United States "should compete with China as effectively as it can on each issue in ways that may be to China's detriment," said Robert Daly, director of the Wilson Center's Kissinger Institute on China and the United States.

"Now we see people who are longtime proponents of the view that the Chinese Communist Party is an existential threat to the United States."

Chinese officials "will tend to see these appointments as proof of what they see anyway: that no matter what they do -- cut a trade deal -- they are facing a United States that is committed to the destruction of the Communist Party," Daly said. "And that will change the nature of the competition."

Trump frequently speaks in terms of dealmaking and has boasted of his relationship with Chinese President Xi Jinping.

But it will ultimately be up to Rubio and Waltz, not Trump, to set the day-to-day "strategic scheme" for US policy, Daly said.

'Best pick' for traditionalists? 

Rubio, like Waltz, is a fervent supporter of Israel, as is Trump's nominee for US ambassador to Israel, evangelical former governor Mike Huckabee.

The son of working-class Cuban immigrants, Rubio is also a vociferous critic of Latin American leftists.

But the senator, unlike many Trump allies, has also backed international causes alongside Democrats, including supporting development assistance to Africa and US global funding to fight HIV/AIDS. 

"Trump isn't picking anyone who hasn't pledged fealty to him. That said, Rubio is probably the best pick that conservative internationalists could have realistically hoped for," said Matthew Waxman, a senior State Department official under former president George W. Bush.

Waxman, now a professor at Columbia Law School, said that Rubio "doesn't suck up to autocrats like some in his party, most importantly the president-elect."

"Republicans are split between internationalists, who believe in exercising American leadership around the world, and isolationists who want to pull out from that role," Waxman said.

"Rubio is much more the former, and his choice will likely disappoint the latter, who brand him as too hawkish."

Allure of the deal 

In a preemptive nod to Trump, Rubio, a longtime critic of Russian President Vladimir Putin, has said that Ukraine is at a stalemate against Moscow's invasion, backing a negotiated solution.

Trump churned through aides in his first term, naming four national security advisors and two secretaries of state as he soured on his team.

His new appointees are certain to know where they stand and how they risk being pushed aside if they disagree, said Allison McManus, managing director for national security and foreign policy at the left-leaning Center for American Progress.

Trump, she said, is likely less concerned about ideology than dealmaking, including on two priorities that eluded Biden -- ending the Gaza war and winning Saudi recognition of Israel.

Trump has even spoken of reaching an agreement with Israel's arch-nemesis Iran, despite walking away from a major diplomatic deal with the country during his first term, which had been negotiated under Barack Obama.

Trump would likely brush aside aides if he believed he can "one-up Biden," McManus said.

"We know that for Trump, his north star is cutting a deal -- especially a better deal than whoever the president was before him," she said.