President-elect Donald J. Trump repeatedly promised voters that he would cut energy and electricity prices in half within 18 months of taking office.

His transition team is just now working on a strategy to accomplish this, according to three people familiar with the discussions who asked for anonymity to discuss internal conversations.

The emerging plan is a repackaging of Mr. Trump’s energy policy. Advisers think Mr. Trump can lower prices by boosting oil and gas production, which is already at record levels in the United States. To pump up production, he plans to quickly approve new drilling projects and pipeline construction and get rid of environmental regulations that the industry says add to its costs.

But energy industry experts noted that a president has limited tools to influence how much Americans pay at the pump, and even less leverage when it comes to electricity prices. More than a dozen experts said Mr. Trump’s strategy might succeed in lowering prices, but not enough to meet his goal.

“It can’t happen,” said Ed Hirs, an energy economist at the University of Houston.

“Good luck,” said Gernot Wagner, a climate economist at Columbia Business School.

“It is not completely impossible, but it is highly unlikely,” said Edmund Crooks, vice chair of the Americas for Woods Mackenzie, an energy consulting firm.