Wind turbines, shown in this 2007 photo, in eastern Washington mesh with the region's huge hydropower system to produce electricity without the release of gases that cause global warming. (Blaine Harden/The Washington Post)

The leaders of the United States, Canada and Mexico will pledge on Wednesday that by 2025 half of their overall electricity generation will come from clean power sources, according to administration officials.

The commitment — which will be a joint one, rather than an individual commitment by each nation — represents an aggressive target given the reliance by the United States and Mexico on fossil fuels for much of their electricity supply. Roughly 59 percent of Canada’s electricity is generated by hydropower operations, with another 16 percent coming from nuclear plants, so it has already surpassed the targeted benchmark.

The new commitment includes not just renewables but also nuclear power, carbon capture and storage plants, and energy efficiency. Under that definition, 37 percent of North America’s electricity in 2015 came from clean energy sources.

President Obama will travel to Ottawa on Wednesday to meet with Canadian Prime Minister Justin Trudeau and Mexican President Enrique Peña Nieto as part of this year’s North American Leaders Summit. The upcoming pledge highlights how collaboration on climate between the United States and Canada has accelerated since Trudeau, leader of his country’s Liberal Party, was elected last fall.

White House senior adviser Brian Deese described it as “an aggressive goal” but one that “is achievable continent-wide.”

He added that the alignment between Canada, Mexico and the United States on climate and energy policy “is stronger than it has been in decades. . . . In all three countries, there is a significant move toward a clean energy economy.”

Roughly 13 percent of U.S. electricity comes from hydropower and other renewable sources, according to the Energy Information Administration, with another 20 percent stemming from nuclear power plants.

[Why the first new U.S. nuclear plant in decades is big news for the climate]

Just 22 percent of Mexico’s electricity generation in 2014 came from non-fossil fuels, according to its government, although leaders there have pledged to raise that figure to 34 percent by 2024.

Mexico will also pledge to reduce its emissions of methane, a powerful greenhouse gas, by 40 to 45 percent by 2025. The United States and Canada have already set that goal for their own methane output.

Deese said the idea that the United States could generate half of its own electricity with clean power by 2025 “is a stretch goal, but one we think is achievable in the United States itself.” But the United States would not have to meet that threshold in order to honor its part of the new North American electricity generation target.

Gwynne Taraska, associate director of energy policy at the Center for American Progress and a co-author of the report, said one of the key elements for averting dangerous warming is that countries must meet current climate goals while also setting more ambitious targets for the future. By teaming up, she said, nations can help one another meet those aspirations.

“When countries work together, you improve the odds of success,” Taraska said.

Democrat Hillary Clinton has said if she’s elected president she will work to ensure that half of the nation’s electric power will come from clean energy sources by 2030. GOP presumptive nominee Donald Trump has emphasized the need to continue extracting fossil fuels, including coal, to power the nation’s electrical grid and has questioned much of the Obama administration’s effort to forge international climate agreements.

Brady Dennis and Chris Mooney contributed to this report.