In many ways, the races were a test of whether Mr. Trump’s strategy of emphasizing short-term pain for long-term gain would resonate with parts of the country battered by, or hostile to, globalization.

“People are willing to deal with some short-term pain to serve a long-term goal,” said Eric Branstad, a former administration official in the Commerce Department who ran Mr. Trump’s campaign in the state two years ago.

“The fact that Trump concluded a deal with Canada and Mexico gave people a sense that things were moving in the right direction,” Mr. Branstad said. “There’s also the trust factor for him here.”