If the conflict with China is not resolved soon, Mr. Trump has threatened to place tariffs on nearly everything China exports to the United States, in addition to tightening Chinese investments in the United States and limiting visas for Chinese citizens. While many supporters describe the president’s bold statements as a negotiating tactic, talks between the Chinese and the United States have faltered for now, with no additional discussions in sight.

“There is no apparent plan,” said Daniel Price, a managing director of Rock Creek Global Advisors, an advisory firm, and a former trade official in the George W. Bush administration. “The administration has given no indication what the off-ramp is or what their objectives are.”

“Trump is treating trade policy as though it were a real estate deal, where the goal is to beat your opponent, step on his throat and humiliate him,” said Daniel Ikenson, the director of trade policy studies at the Cato Institute.

Even if it works and nations like China blink, Mr. Ikenson said, “the cost to that will be trust in the U.S., and it will encourage other governments to behave this way when their backs are against the wall.”

Many farmers and manufacturers remain staunch supporters of Mr. Trump. But their faith is starting to waver as tariffs take effect and they feel the impact of reduced market access and higher costs.

“I would just like the administration to be clear, at least with us, on the goal,” said Jay Hollowell, the mayor of Helena-West Helena, Ark., an area that produces soybeans, which are now being heavily taxed by China. “Is it to lower trade deficits with other countries like China, or is it to protect American industries?”