“Of course I’m concerned because the price of oil is dropping like crazy right now,” said Darlene S. Wallace, president of Columbus Oil, a small Oklahoma producer. “I was making a profit this year for the first time in four years, and now it doesn’t look like it will end up that way toward the end of the year.”

But the drop in prices has clearly been a boon to people and businesses that use oil.

Americans consume roughly 400 million gallons of gasoline a day, so every time prices fall by a penny they save about $4 million. The average retail price for regular gasoline is about $2.50 a gallon, according to AAA, about the same as a year ago. But that is $1.60 a gallon less than it was a decade earlier, when the shale-oil boom was just starting.

In addition to the benefits of lower prices for consumers, Mr. Trump appears to want a well-supplied oil market so he can press countries to cut their imports from Iran without worrying about running out of fuel. Lower energy costs should also tamp down inflation, which in turn would help keep interest rates low at a time when some analysts fear an economic slowdown.

The president might have some success in getting Saudi Arabia not to cut oil production because of how he has handled the killing of the journalist Jamal Khashoggi in the Saudi Consulate in Istanbul. Thankful for Mr. Trump’s public support, the Saudi crown prince, Mohammed bin Salman, might be more willing to tolerate low oil prices than he would have been otherwise.

Russia also appears to be in no hurry to cut production, which is at the record level of roughly 11 million barrels a day. Igor Sechin, chief executive of the Russian oil company Rosneft and an influential ally of President Vladimir V. Putin, has aggressively promoted drilling at home and abroad. Mr. Putin recently said he was satisfied with the current price of oil.