US Senator Marco Rubio painted a dark vision of the consequences of America’s “unbalanced relationship” with China, echoing President-elect Donald Trump’s anti-globalist rhetoric as he vies to be confirmed as his secretary of state.

While touching on issues plaguing the Middle East, Latin America and eastern Europe, Rubio focused much of his five-hour Senate confirmation hearing warning that without swift and substantive policy shifts, China will remain the “biggest threat” to American prosperity in the 21st Century.

“If we don’t change course, we are going to live in the world where much of what matters to us on a daily basis from our security to our health will be dependent on whether the Chinese allow us to have it or not,” Rubio testified to the Senate Foreign Relations Committee on Wednesday.

Asked about NATO, the 75-year-old security organisation that Trump has repeatedly criticised, Rubio affirmed its value, calling it a “very important alliance.”

But Rubio endorsed Trump’s view that some European allies should be contributing more to their collective defence, adding that the US must decide whether it wants “a primary defence role” or to be a “backstop” against aggression.

The 53-year-old Republican made the case against China and other US adversaries to his colleagues on the Foreign Relations panel where he served for 14 years.

He received a warm welcome from both sides of the aisle, making jokes about how “surreal” it was to be on the other side of the dais.

But in between the niceties, Rubio blamed America’s vulnerability to China on the shift to globalism, which he says “is now a weapon being used against us.” He said the US must begin placing “our core national interests above all else.”

It’s a remarkable opening salvo from Rubio, who was born in Miami to Cuban immigrants and who, if confirmed, would become the first Latino to serve as the nation’s top diplomat.

The confirmation hearing begins a new chapter in the political career of the third-term senator, whose relationship with Trump has evolved over the last decade.

Once rivals trading schoolyard insults as they campaigned for president in 2016, the two men became close allies as Trump campaigned for another White House term last year.

If confirmed, Rubio will become the leader of US foreign policy — though his role will surely remain secondary to Trump, who relishes the global stage and frequently uses the bully pulpit against America’s allies.

Unlike many of Trump’s Cabinet selections, Rubio is expected to easily win confirmation, notching support not only from Republicans but also Democrats who endorse him as a “responsible” pick to represent the US abroad.

Many expect he will be among the first of Trump’s Cabinet picks approved.