The 10 percent tariff the president said he might impose in March could cause U.S. refineries to cut production and lead to higher prices.

Some oil refineries will probably struggle to replace imported crude oil if President Trump imposes 25 percent tariffs on products from Canada and Mexico.

Oil and gas executives welcomed President Trump’s early moves on energy policy, but many said they did not plan to increase production unless prices rose significantly.

The president said he’d declare an energy emergency, increase drilling and end support for electric cars. His pivot to oil and gas follows the hottest year in recorded history.

The industry is pumping ever more oil and natural gas, but it is doing so with only about three-quarters as many workers as it employed a decade ago.

Constellation Energy’s deal to buy Calpine is being driven by fast-rising demand for electricity in part by the technology industry’s investments in artificial intelligence.

The lawsuit, an unusual strategy for the oil giant, comes after California’s attorney general sued Exxon last year alleging it misled the public about plastics recycling.