With Mr. Trump’s re-election campaign approaching, he and his advisers are increasingly conscious of the need to limit any economic damage, particularly among key political constituencies like farmers, who have suffered the most.

The American farm economy has stumbled into recession, hurt by a sharp drop-off in sales to China, among the largest export markets for agricultural goods like soybeans, pork and corn. While the administration has tried to blunt the pain with two rounds of financial assistance, farmers have increasingly pleaded with the White House to end the trade war, saying the handouts are not enough to make up for the lost sales.

That pain was set to get worse next week. Until Friday’s truce, Mr. Trump had planned to increase tariffs on $250 billion worth of goods to 30 percent from 25 percent, a hike that would likely have been met with further retaliation by China and been particularly burdensome for consumers and businesses going into the holiday season.