TOLEDO, Ohio — President Trump’s supporters nodded approvingly last week as Mr. Trump extolled the “big, beautiful monster” of a trade deal that he will sign with China on Wednesday.

The enthusiastic group, gathered at Toledo’s Huntington Center, nodded again as Mr. Trump insisted that America’s farmers, who have been hurt by the trade war with China, were winners and as he asserted, incorrectly, that American importers were not paying for the tariffs.

“And now the deal is done,” Mr. Trump said.

The packed arena roared triumphantly.

On Wednesday, Mr. Trump will sign an initial trade agreement with Beijing that will help cool tensions between the world’s two largest economies but leaves many of the biggest issues unresolved. Key details of the agreement remain murky, the text remains under wraps and more complicated matters, like China’s financial support for companies that compete with American firms, have been pushed until after the 2020 election.

But to Mr. Trump’s most faithful backers, the president took on China and scored a major win.

“Instead of giving all the money to China, now we’re going to get some of it back,” said Kim Lewis, 65, a corn and soybean farmer from Jamestown, Ind., who drove four hours to see Mr. Trump’s speech. “He had the guts to stand up to these other countries.”