Is the climate for the North American Free Trade Agreement (NAFTA) and trade in general beginning to warm as the Midwest trudges through a chilly winter? There are some optimistic signs.

Iowa Sen. Joni Ernst last week told a meeting of farmers that she is sensing some softening in the Trump administration’s concerns about maintaining NAFTA. “I think he has doubts (about pulling out of NAFTA),” Ernst told a meeting of the Iowa Corn Growers Association in Tama.

Others are also getting a warmer feeling about NAFTA’s future. They say persistent...