President-elect Donald Trump named Marco Rubio of Florida as his nominee for secretary of state on Wednesday, setting up a one-time critic who evolved into one of the president-elect’s fiercest defenders to become the nation’s top diplomat.

The conservative politician is a noted hawk on China, Cuba and Iran, and was a finalist to be Mr Trump’s running mate this summer.

On Capitol Hill, Mr Rubio is the vice chairman of the Senate intelligence committee and a member of the Senate foreign relations committee. He has pushed for taking a harder line against China and has targeted social media app TikTok because its parent company is Chinese.

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Marco Rubio was once one of Donald Trump’s harshest critics (Wilfredo Lee/AP)

He and other politicians contend that Beijing could demand access to the data of users whenever it wants.

Mr Trump said: “He will be a strong advocate for our nation, a true friend to our allies, and a fearless warrior who will never back down to our adversaries.”

The president-elect made the announcement while flying back to Florida after a meeting with President Joe Biden in Washington.

The selection is the culmination of a long, complicated history between the two men.

During their tense competition for the Republican presidential nomination in 2016, Mr Rubio was especially blunt in his criticism of Mr Trump, calling him a “con artist” and “the most vulgar person to ever aspire to the presidency”.

He tried to match Mr Trump’s often-crude attacks by joking about the size of Mr Trump’s hands.

Mr Trump responded by branding Mr Rubio as “little Marco”, a nickname that stuck with the senator for years.

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Tulsi Gabbard will serve as director of national intelligence (Alex Brandon/AP)

But like many Republicans who sought to maintain their relevance in the Trump era, Mr Rubio shifted his rhetoric.

As speculation intensified that Mr Trump might pick him as his running mate, Mr Rubio sought to play down the tension from 2016, suggesting the heated tone simply reflected the intensity of a campaign.

“That is like asking a boxer why they punched somebody in the face in the third round,” Mr Rubio told CNN when asked about his previous comments. “It’s because they were boxing.”

Elsewhere, Mr Trump selected Tulsi Gabbard, a former Democratic member of Congress and presidential candidate, to serve as director of national intelligence and Matt Gaetz to be his attorney general.

In a statement, the president-elect said: “As a former candidate for the Democrat presidential nomination, she has broad support in both parties – she is now a proud Republican!

“I know Tulsi will bring the fearless spirit that has defined her illustrious career to our intelligence community, championing our constitutional rights, and securing peace through strength. Tulsi will make us all proud!”

In selecting Mr Gaetz, Mr Trump passed over some of the more established attorneys whose names had been mentioned as being contenders for the job.

Mr Trump said: “Matt will end weaponised government, protect our borders, dismantle criminal organisations and restore Americans’ badly shattered faith and confidence in the justice department.”