President-elect Donald Trump planed on Tuesday to nominate Exxon Mobil Corp. chief Rex Tillerson for U.S. secretary of state, setting off a confirmation fight that puts the oilman's ties to Russian President Vladimir Putin — and Trump's own — in the spotlight.

The nomination is sure to spark a high-profile battle in the U.S. Senate, where three Republicans and several Democrats have already expressed public misgivings about making Tillerson the nation's top diplomat, largely over concerns about his two decades of work with Putin.

Tillerson has accepted Trump's offer, according to a person familiar with the transition. He will reach Exxon's mandatory retirement age of 65 in March and, if confirmed, would be the first oil executive to lead the State Department.