The angry mutterings at the Permian Basin Petroleum Association’s “Spring Swing” golf tournament this week weren’t all about missed putts or lost balls. The Texas oilmen on the fairways had a more serious concern: The president they helped elect was tanking oil prices.

For years, Texas drillers were riding high, helping make the U.S. the top oil producer in the world. They backed Trump for cutting red tape and boosting oil-friendly policies. But now? His trade war and new tariffs are rattling the market. Oil prices have dropped to around $57 a barrel—not nearly enough for many companies to turn a profit.

Eager to stay in Mr. Trump’s good graces, oil executives refrain from publicly criticizing the president. But privately, ‘Everybody’s afraid.’