Kirsten Hillman, Canada’s ambassador to the United States and the country’s chief negotiator on U.S. trade, plans to leave the job in the new year.

She is expected to be replaced by Canadian financier Mark Wiseman, a close friend of the Prime Minister, the source said.

The Globe and Mail is not identifying the source because they were not authorized to publicly discuss the matter.

In June, Prime Minister Mark Carney had asked Ms. Hillman to stay on as ambassador to Washington and take on the role of chief negotiator in tense trade and security talks with the Trump administration. But Ms. Hillman had made it clear she did not want to say in the job for very long.