Bloomberg cited sources as saying an announcement was due on Tuesday about Blinken's appointment. The transition team of Biden declined comment and a request for comment was not answered by Blinken.

A Biden ally, who didn't want to be named, said Biden's most likely option was Reuters Blinken and an announcement was anticipated as soon as this week.

Blinken is Biden's former confidante.

Blinken said the United States would not cede its leadership position in the world in an interview with Reuters in October.

"As much of a burden as it sometimes seems to play ... the alternative in terms of our interests and the lives of Americans are much worse," he said.

Blinken, 58, is characterized by individuals familiar with his management style as a "diplomat's diplomat," deliberative and relatively soft-spoken, but well-versed in the nuts and bolts of foreign policy.

Blinken became one of the founders of WestExec Advisors, a Washington firm advising companies on geopolitical threats, after Democratic presidential candidate Hillary Clinton lost the 2016 election to President Donald Trump.

Blinken, born in New York City and educated at Harvard, practiced law briefly.

He entered the White House of Democratic President Bill Clinton as a speechwriter, becoming one of his national security aides.

Blinken worked under Obama to restrict most U.S. military deployments to limited numbers of troops. But last year, he told Reuters that with his pullback of U.S. soldiers in Syria in 2019 that left Kurdish U.S. allies in the lurch in their war against the Islamic State, Trump "gutted American credibility"

Blinken served alongside Biden as an advisor to his failed presidential campaign in 2008, his national security adviser early in his vice presidency, and as the Democratic staff chief of the International Affairs Committee of the Senate while Biden was president.