US President-elect Donald Trump has praised Exxon Mobil CEO Rex Tillerson, amid growing reports he is going to appoint him secretary of state.
In an interview with Fox News, Mr Trump called Mr Tillerson, 64, a "world-class player" who has made "massive deals".
As Exxon CEO Mr Tillerson has had business ties with Russia's leadership and is said to have a good relationship with President Vladimir Putin.
He has criticised sanctions against Russia for its annexation of Crimea.
In an interview Fox News Sunday, Mr Trump praised Mr Tillerson, saying: "He's a world-class player. He's in charge of an oil company that's pretty much double the size of its next nearest competitor."
Mr Trump added that Mr Tillerson knows many of the players and he knows them well. He does massive deals in Russia."
Republican Senator John McCain expressed "concern" about Mr Tillerson's potential links to Russian President Vladimir Putin, whom the senator called "a thug, a bully and a murderer", during an interview with Fox News on Saturday.
However, speaking on to CBS on Sunday, he said the Senate would give Mr Tillerson a "fair hearing" should he be selected by Mr Trump.
Mr Tillerson is likely to be named America's top diplomat next week. NBC News reports that ex-US ambassador to the UN John Bolton may serve as his deputy.
Former New York City Mayor Rudy Giuliani withdrew himself from consideration for the post last week.
Under scrutiny: Analysis by Barbara Plett Usher, BBC News, Washington
This is the latest twist in Donald Trump's weeks-long search for a top diplomat: he has been considering close to a dozen candidates with significantly different views and backgrounds.
Transition officials say he has finally settled on Rex Tillerson although there has been no official announcement.
The long-time oil executive does not have any diplomatic experience but he has done business with many foreign governments, including in Russia where he has developed a good relationship with President Vladimir Putin.
That is one reason his nomination would be closely scrutinised by lawmakers - especially in the wake of intelligence assessments that Russian hackers acted covertly to promote Mr Trump's campaign.