En route to New Orleans, where the president and his wife, first lady Jill Biden, will attend an interfaith prayer service to commemorate those who died in the New Year’s Day terrorist attack, White House press secretary Karine Jean-Pierre described Trudeau as “a stalwart friend” of the United States during his decadelong prime ministership.

“We have worked closely together on the full range of issues facing our countries and the world as close allies, neighbors, and as members of the G7,” Jean-Pierre told reporters Monday on Air Force One. “The president is grateful for the prime minister’s partnership on all of that and for his commitment to defending North America from the geopolitical threats of the 21st century and the work we have done together to sustain North America’s status as the world’s most economically competitive region.”

The press secretary also conveyed Biden’s support to the Canadian people as Trudeau’s Liberal Party elects a new leader.

Trudeau announced his decision Monday during a press conference convened after months of speculation that he, like Biden, would be replaced before Canada’s next election, which has to be held before Oct. 20. Amid his declining popularity, speculation was further stoked by his deputy prime minister and finance minister, Chrystia Freeland, standing down from his Cabinet last month.

“I intend to resign as party leader, as prime minister, after the party selects its next leader through a robust, nationwide, competitive process,” Trudeau said Monday in Ottawa. “Removing me as the leader who will fight the next election for the party should decrease the polarization that we have right now.”

Trudeau has been perceived as the wrong leader to counter President-elect Donald Trump, who has repeatedly mocked him as the “governor” of Canada after threatening to impose 25% tariffs on Canada if it does not help the U.S. secure their shared border.

“Many people in Canada LOVE being the 51st State. The United States can no longer suffer the massive Trade Deficits and Subsidies that Canada needs to stay afloat. Justin Trudeau knew this, and resigned,” Trump wrote on social media.

Trudeau will remain Canada’s prime minister until March 24, when the Canadian Parliament is expected to resume. He became the Liberal Party’s leader in 2013 and prime minister two years later.