US President Barack Obama has admitted that the transition period leading to Donald Trump's inauguration has been "unusual" and warned that the CEO's "improvisational" style might not translate well to the presidency.
In excerpts of an interview with the CBS news program "60 Minutes" released on Friday, Obama laid bare some of the tensions between the 44th and the soon-to-be 45th president.
"It's unusual," Obama said in the interview, to air in full on Sunday.
"I suspect the president-elect would agree with that. Look, he was an unconventional candidate."
But Obama also cautioned that Trump's freewheeling style will be put to the test in the Oval Office.
"It'll be a test, I think, for him and the people that he's designated to be able to execute on his vision," he said.
"Don't underestimate the guy, because he's going to be 45th president of the United States," Obama added.
"The one thing I've said to him directly, and I would advise my Republican friends in Congress and supporters around the country, is just make sure that as we go forward, certain norms, certain institutional traditions don't get eroded, because there's a reason they're in place."