The first time Donald J. Trump ran for president, he slapped on a miner’s helmet and told coal workers they would be “winning, winning, winning” when he entered the White House.

Now, as Mr. Trump campaigns for another chance at the presidency, he rarely mentions America’s coal miners and has stopped making grand promises about their future.

The shift reflects political and economic realities, experts said. Top among them: Mr. Trump oversaw coal’s decline, not its salvation. Despite the fact that Mr. Trump gutted climate regulations and appointed a coal lobbyist to lead the country’s top environmental agency, 75 coal-fired power plants closed and the industry shed about 13,000 jobs during his presidency.

“Not a single coal miner went back to work or power plant saved,” said Erin E. Bates, a spokeswoman for the United Mine Workers of America, the labor organization representing coal miners.

“I think he’s realizing those promises were not met during his term and they’re probably not going to be met now,” she said. “Politically, it probably doesn’t pay for his campaign to make more broken promises.”

Two decades ago, coal produced about half of all the electricity in the United States. Today, it accounts for just 16 percent of American power generation. The industry employed nearly 180,000 people at its peak in the 1980s, but now that figure is about 44,800, according to the U.S. Bureau of Labor Statistics.