Democratic officials say President Barack Obama intends to nominate Montana Sen. Max Baucus as ambassador to China.
The nomination is subject to Senate confirmation. The Democrat had announced earlier this year that he would not seek re-election.
The 72-year-old Baucus is chairman of the Senate Finance Committee, with jurisdiction over taxes, trade and other areas.
He was instrumental in efforts to pass Obama's health care law four years ago and has spent much of this year seeking to build support for a sweeping overhaul of the tax code.
There was no immediate comment from the White House.
The officials spoke on condition of anonymity because they weren't authorized to publicly discuss the nomination in advance of Obama's announcement.
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