The White House is expected to nominate Max Baucus, the retiring long-time senator from Montana, to be the next US ambassador to China, according to sources familiar with the matter.
The surprise appointment of Mr Baucus, who would replace Gary Locke as ambassador in Beijing, comes at a time when tensions between the US and China appear to be rising over military issues in Asia.
Mr Baucus, 72, has already said that he will not run for re-election in 2014, and if his appointment takes place before November, he would have to give up his powerful position as chairman of the Senate finance committee. He would need to be confirmed by his fellow senators for the position.