WASHINGTON — President Trump announced Thursday that he will withdraw the United States from participation in the Paris climate accord, weakening global efforts to combat climate warming and siding with conservatives who argued that the landmark 2015 agreement was harming the economy.

But he will stick to the withdrawal process laid out in the Paris agreement, which President Barack Obama joined and most of the world has already ratified. That could take nearly four years to complete, meaning a final decision would be up to the American voters in the next presidential election.

Still, Trump’s decision is a remarkable rebuke to fellow heads of state, climate activists, corporate executives, and members of the president’s own staff, all of whom failed this week to change Trump’s mind with an intense, last-minute lobbying blitz.

It makes good on a campaign promise to “cancel’’ an agreement he repeatedly mocked and derided at rallies, saying it would kill US jobs. As president, he has moved rapidly to reverse Obama-era policies designed to allow the United States to meet its pollution-reduction targets as set under the agreement.

“In order to fulfill my solemn duty to protect America and its citizens, the United States will withdraw from the Paris climate accord but begin negotiations to reenter either the Paris accord or an entirely new transaction on terms that are fair to the United States,’’ the president said. “We are getting out. But we will start to negotiate, and we will see if we can make a deal that’s fair. And if we can, that’s great.’’

Trump said that the United States will immediately “cease all implementation of the nonbinding Paris accord’’ and what he said were “Draconian financial’’ and other burdens imposed on the country by the accord.

In his remarks, Trump listed sectors of the US economy that would suffer lost revenues and jobs if the country remained part of the accord, citing a study — disputed vigorously by environmental groups — that says the agreement would cost 2.7 million jobs by 2025.

Obama, in a rare assertion of his political views as a former president, castigated the decision.

“The nations that remain in the Paris Agreement will be the nations that reap the benefits in jobs and industries created,’’ he said in a statement. “I believe the United States of America should be at the front of the pack.’’

John F. Kerry, who had made addressing global change a cornerstone of his work as a senator from Massachusetts and the forging of the Paris accords a centerpiece of his accomplishments as secretary of state, bitterly denounced the withdrawal.

“The president who promised ‘America First’ has taken a self-destructive step that puts our nation last. This is an unprecedented forfeiture of American leadership which will cost us influence, cost us jobs, and invite other countries to walk away from solving humanity’s most existential crisis,’’ he said in a statement. “It isolates the United States after we had united the world.’’

He later lambasted Trump in an interview with MSNBC: “He’s made us an environmental pariah in the world, and I think it is one of the most self-destructive moves I have ever seen by any president in my lifetime.’’

Most Republicans lauded the decision.

“I applaud President Trump and his administration for dealing yet another significant blow to the Obama administration’s assault on domestic energy production and jobs,’’ said Senator Mitch McConnell of Kentucky, the majority leader.

Senator John Barrasso, Republican of Wyoming and chairman of the Senate Committee on Environment and Public Works, said, “The Paris climate agreement set unworkable targets that put America at a competitive disadvantage with other countries and would have raised energy costs for working families.’’

But Republican Senator Susan Collins of Maine wrote on Twitter, “Climate change requires a global approach. I’m disappointed in the President’s decision.’’

In recent days, Trump withstood withering criticism from European counterparts who accused him of shirking the United States’ role as a global leader and its responsibility as the world’s second-largest emitter of planet-warming greenhouse gases. And he shrugged aside pleas from business executives who said the decision will damage the environment and hamper their efforts to compete.

Trump also found himself at the center of a bruising, monthslong debate inside the White House that pitted senior members of his staff against each other.

The president’s decision was a victory for Stephen Bannon, his chief strategist, and Scott Pruitt, his Environmental Protection Agency administrator, both of whom had argued forcefully to abandon the global pact in favor of a break that would clear the way for a new environmental approach.

Other top aides, including Gary D. Cohn, director of the National Economic Council; the president’s daughter Ivanka Trump; and his secretary of state, Rex Tillerson, had insisted that remaining a part of the agreement would have allowed the United States to eviscerate Obama-era climate rules without as much damage to relations with other countries.

Supporters of the Paris Agreement reacted with pent-up alarm, condemning the administration for shortsightedness about the planet and a reckless willingness to shatter longstanding diplomatic relationships.

“This is disgraceful,’’ said Annie Leonard, Greenpeace USA’s executive director. “By withdrawing from the Paris Climate Agreement, the Trump administration has turned America from a global climate leader into a global climate deadbeat.’’

Corporate leaders also condemned Trump’s action. In a statement, IBM took issue with the president’s contention that it is a bad deal for American workers. “This agreement requires all participating countries to put forward their best efforts on climate change as determined by each country,’’ the company said.

But Trump was resolute.

“It is time to put Youngstown, Ohio, Detroit, Michigan, and Pittsburgh, Pennsylvania, along with many, many other locations within our great country before Paris, France,’’ he said. “It is time to make America great again.’’

Pittsburgh Mayor Bill Peduto responded on Twitter, “I can assure you that we will follow the guidelines of the Paris Agreement for our people, our economy & future.’’