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Mark Wiseman in New York in November, 2017. Conservative and Bloc Québécois MPs have seized on a 2023 tweet from Mr. Wiseman that has been interpreted by some as being anti-Quebec.Mike Segar/Reuters

Opposition parties are warning Prime Minister Mark Carney against appointing a long-time friend and wealthy financier as Canada’s ambassador to Washington.

The U.S. envoy post opened after Ambassador Kirsten Hillman announced Tuesday that she will leave Canada’s most important diplomatic position in the new year.

A source has told The Globe and Mail that Canadian financier Mark Wiseman, a close friend of Mr. Carney, is being considered to replace Ms. Hillman. The Globe is not naming the source who was not authorized to discuss the matter.

In the House of Commons Wednesday, Conservative and Bloc Québécois MPs seized on comments that Mr. Wiseman made as the co-founder of the Century Initiative. The non-profit organization advocates increasing Canada’s population to 100 million by 2100 solely through immigration.

Mr. Wiseman was quoted in a May, 2023 tweet as saying that “100 million may not be federal policy, but it should be – even if it makes Quebec howl.”

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Conservative Leader Pierre Poilievre told the House that Mr. Wiseman should not be named to the Washington position because “this is someone who has shown contempt for Quebec and cannot negotiate for Quebec.”

Bloc MP Christine Normandin chimed in that Mr. Wiseman is not qualified to represent the interests of Quebec in Washington.

Both Government House Leader Stephen MacKinnon and Dominic LeBlanc, the minister responsible for Canada-U.S. trade, said the Century Initiative’s call for 100 million population “is not government policy and never will be.”

During the leadership campaign, Mr. Carney promised to cap immigration until it returned to sustainable, pre-COVID levels.

Last month, the government released its annual immigration targets. It significantly cut the number of temporary residents, including reducing international students by half.

Ottawa effectively froze the number of new permanent residents over the next three years. It aims to admit 380,000 new permanent residents each year until 2027. That’s down from just two years ago, when the former Justin Trudeau government was aiming for half a million a year,

The Conservatives also noted that Mr. Wiseman has been quoted as being opposed to supply management, arguing that it inhibits productivity.

Supply management has been in place for dairy, poultry and eggs since the 1970s. The federally mandated policy sets production limits and import controls to restrict supply and stabilize pricing for farmers.

Supply management is expected to be on the table when Canada’s continental trade partners renegotiate the United States-Mexico-Canada Agreement next year.

Mr. LeBlanc told the House that “we will not negotiate supply management with the Americans,” even though President Donald said he wants the Canadian market to be more open to imports from U.S. farmers.

The Prime Minister was not in Question Period Wednesday. When questioned by reporters at a Liberal caucus meeting earlier in the day, he declined to say whether Mr. Wiseman will be named ambassador.

However, Mr. Carney said the appointment will be made soon. He added that Canada’s next ambassador to Washington will have a window to prepare for the next phase of trade relations with the U.S.

Mr. Wiseman has no diplomatic or government experience, but he is a veteran institutional investor. He was formerly chair of the Alberta Investment Management Corporation, a top manager at BlackRock (the world’s largest asset manager) and CEO of the Canada Pension Plan Investment Board.

In March, 2025, the Prime Minister named Mr. Wiseman to his council of advisers on Canada-U.S. relations.

Ms. Hillman told The Globe Tuesday that the timing of her departure gives the Prime Minister the ability to put “a team in place” as negotiations get under way on the review of the USMCA.

Ms. Hillman would not say who will replace her. But she said that the next ambassador must quickly build bridges with Mr. Trump’s White House, senior cabinet secretaries and congressional leaders. The new ambassador must also reach out to Mr. Trump’s business and political allies outside Washington, she said.

Above all, she said, it’s important to listen to what Mr. Trump says and “to find a path forward that works for Canada.”