Other state and local officials also soon announced they would step up. Mark Dayton, the Democratic governor of Minnesota, said his state would pursue the Paris goals. And dozens of mayors across the country said they would continue to work to reduce greenhouse-gas emissions from their cities. Their number included Mitch Landrieu, a Democrat of New Orleans, and Jim Brainard, the longtime Republican mayor of Carmel, Indiana.

They may soon have a venue to do so. More than 30 mayors, 80 university presidents, and 100 businesses will soon submit their own emissions-reductions plan under the Paris Agreement, announced Michael Bloomberg, the former mayor of New York City, on Friday. They will call it “America’s Pledge.”

Bloomberg, currently the UN special envoy on cities and climate change, has also committed his philanthropical organization to donating $15 million in funding to the UN for climate-coordination efforts. Trump pledged to cancel an equal amount in his Thursday speech.

“Today, we want the world to know: The U.S. will meet our Paris commitment, and, through a partnership among American cities, states, and businesses, we will seek to remain part of the Paris Agreement process,” said Bloomberg in a statement. He said that the group will “aim to meet the U.S. commitment to reduce our emissions 26 percent below 2005 levels by 2025.”

“We are already halfway there—and we can accelerate our progress further, even without any support from Washington,” he added.

The politics of such a move are not hard to figure out. For mayors and governors with urban, college-educated, and especially younger constituents—in other words, for politicians whose voters do not resemble Trump’s—climate change is a winning issue. (Though some of the most climate-friendly actions they could take, like investing in public transit and supporting denser housing, may be less popular, as Josh Barro writes.)

“Look, Donald Trump has absolutely chosen the wrong course. He’s wrong on the facts. California’s economy and America’s economy are boosted by following the Paris Agreement,” said Jerry Brown, the governor of California and a Democrat. He shared a press conference with Christiana Figueres, the former UN diplomat who led the negotiations that produced the Paris Agreement.

“The Californian economy increased 40 percent faster than the rest of the [U.S.] economy last year,” he added, despite “following policies that are even tougher than what Paris is calling for.” California has had some of the most stringent climate-change policies in the developed world since Arnold Schwarzenegger, a former Republican governor, called for them and signed them into law in 2006.

“Today’s announcement by the president leaves the full responsibility of climate action on states and cities throughout our nation,” said Jay Inslee, the Democratic governor of Washington, in a statement. “While the president’s actions are a shameful rebuke to the work needed to protect our planet for our children and grandchildren, states have been and will continue to step up.”