OTTAWA — Canada’s ambassador to the United States and its chief trade negotiator with the Trump administration said she is stepping down in the new year.

“I have advised Prime Minister [Mark] Carney that I will be ending my tenure in the United States in the New Year. It has been the greatest privilege of my professional life to have served and represented Canada and Canadians during this critical period in Canada-U.S. relations,” Kirsten Hillman said in her resignation letter posted on X on Tuesday afternoon.

Hillman’s departure comes after eight years in Washington, as the Carney government navigates President Donald Trump’s abrupt cancellation of bilateral trade talks in October and prepares for next year’s review of the United States-Mexico-Canada Agreement.

Hillman, a trade lawyer and career diplomat, was a key member of the Canadian negotiating team that faced off against Trump’s first administration during the talks that led to the creation of the USMCA.

“While there will never be a perfect time to leave, this is the right time to put a team in place that will see the CUSMA Review through to its conclusion,” she wrote, using the Canadian acronym for the new North American trade pact.

Despite the current trade disruptions and the aftermath of navigating the Covid-19 pandemic, Hillman said her greatest accomplishment was working to secure the release of two Canadian men who spent more than 1,000 days arbitrarily imprisoned in China from 2018 to 2021.

“In a relationship as deep and complex as ours, pressing and consequential issues arise almost daily,” she wrote. “Yet none was more personal to me than the hundreds of hours I spent with U.S. and Chinese counterparts working for the release of Michael Kovrig and Michael Spavor.”