But voters in the district say the escalating trade drama has already begun to complicate their daily lives. Companies that supply construction materials have suspended orders, waiting to see what happens to metal prices. Employees at a builder of truck components say managers have been hastily reassessing supply chains that run through China and Mexico. A local hard-cider brewer is reconsidering an expansion after the steel and aluminum tariffs made new tanks and cans more expensive.

And at Boeing, a company that employs grandfathers next to granddaughters and has introduced generations of Washingtonians to their spouses, the unease has been evident from the executive suite to the factory floor.

Mr. Trump’s hard line on trade didn’t used to inspire so much teeth-grinding among Boeing workers. A lot of union mechanics were happy last year when he pulled out of the Trans-Pacific Partnership, which would have reinforced the nation’s embrace of free trade. And the president earned a lot of fans in Washington when he criticized the company on the campaign trail in 2015 for setting up a new plant outside Shanghai, saying it would “end up taking a tremendous number of jobs away from the United States.”

Jim McKenzie, a union machinery repairman, remembered that comment when, several months ago, he came across a package of dorsal-fin parts at the Boeing plant in Auburn where he works. Mr. McKenzie pulled back the Bubble Wrap and saw a label that made him feel as if he were sinking into quicksand: Boeing China.

“We drill it and assemble it, but they ship the parts in from China,” Mr. McKenzie said. “There are people who have worked here for 25 years making those parts, and they’re proud of that.”

But Mr. McKenzie, 56, isn’t eager to blow up the Beijing relationship. “China will just buy all their planes from Airbus,” he said, leaning his chair back against a wall in the machinists’ union hall in Auburn.