BISMARCK, N.D. (AP) — Presumptive Republican presidential candidate Donald Trump unveiled an “America first” energy plan he said would unleash unfettered production of oil, coal, natural gas and other energy sources to push the United States toward energy independence.

But the speech, delivered at the annual Williston Basin Petroleum Conference in Bismarck, North Dakota, went far beyond energy, as Trump laid out, in his most detail to date, a populist general election pitch against likely rival Hillary Clinton.

“She’s declared war on the American worker,” Trump said of Clinton, reading from prepared remarks in a stadium packed with thousands.

Trump delivered the policy address just hours after The Associated Press determined he had won the number of delegates needed to clinch the Republican presidential nomination. He focused on coal, in particular, to help make his case against Clinton, his likely Democratic opponent in the general election.

In March, Clinton said, “We’re going to put a lot of coal miners and coal companies out of business.” She has since walked back the remark, calling it “a misstatement” and outlining a plan to help displaced coal workers.

Trump said Thursday he would do everything he could “free up the coal” and bring back thousands of coal jobs lost amid steep competition from cheaper natural gas and regulations designed to cut air pollution and reduce greenhouse gases blamed for global warming.

“They love it,” Trump said of those who work in coal mines. “We’re going to bring it back and we’re going to help those people because that’s what they want to do.”

The comment marked a shift from a remark Trump made in a 1990 interview with Playboy Magazine, when he compared his career in real estate to “the story of the coal miner’s son.”

“The coal miner gets black-lung disease. His son gets it, then his son. If I had been the son of a coal miner, I would have left the damn mines,” he told Playboy. “But most people don’t have the imagination — or whatever — to leave their mine.”

Asked Thursday about the Playboy comment, Trump responded in an email. “I never had the imagination to leave the real estate industry, until I recently decided to make America great again,” he said. “We tend to follow up our father’s footsteps, and that’s the lifestyle we want, even if it’s tougher than other alternatives. … Being a coal miner is really tough, but that’s what they love and unlike Hillary Clinton, I am going to make sure they have they have their jobs for many years to come.”

Trump also promised Thursday to cancel the Paris climate agreement and stop all payments of U.S. tax money to a United Nations fund to mitigate effects of climate change worldwide.

He is among many Republicans who reject mainstream climate science. He has called climate change a “con job” and a “hoax” and suggested it is a Chinese plot “to make U.S. manufacturing non-competitive.”

He accused President Barack Obama of doing “everything he can to get in the way of American energy.”

Trump’s comments were out of step with an ongoing oil boom that has raised U.S. production to record level and cut gas prices to about $2.30 per gallon. The United States has been the world’s top producer of petroleum and natural gas for the last four years, according to the Energy Department.

Since Obama took office in 2009, U.S. onshore crude oil production has increased by nearly 90 percent.

Michael Brune, executive director of the Sierra Club, said Trump’s “so-called energy plan” was “an unmitigated disaster. It’s clear that Donald Trump would bankrupt our air, water and climate just like he’s bankrupted his businesses.”

Brune called Trump a climate-change denier and said “his fossil fuel comeback plan is a dirty fantasy disconnected from economic realities and our moral imperative to transition to clean energy. There are open pools of oil in North Dakota right now that are deeper than Trump’s understanding of energy issues.”

North Dakota is at the heart of America’s oil boom and now is the second largest oil-producing state after Texas, thanks largely to huge reserves in the oil-rich Bakken region and advances in fracking and other drilling technology.

Despite his political position on climate, there is evidence Trump the businessman is moving to hedge his bets.

Earlier this month, one of Trump’s companies specifically cited sea level rise and increased storminess fueled by global warming in paperwork seeking permission to build a nearly two-mile-long stone wall to fortify the shoreline at one of his golf courses in Ireland.

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Associated Press writers Steve Peoples, Michael Biesecker, Erica Werner and Julie Pace in Washington contributed to this report.