Before this month, New Balance was lucky if it generated a few hundred reactions to posts on its Facebook page. Now, the sneaker company’s pageis flooded with impassioned commentary, and it has found itself compelled to make a statement distancing itself from white supremacists.

It started, when Matt LeBretton, the company’s vice president for communications, told The Wall Street Journal last week that “we feel things are going to move in the right direction” under Donald J. Trump. Mr. LeBretton’s comments were made in the context of Mr. Trump’s opposition to the Trans-Pacific Partnership, a trade deal that New Balance says will hurt its production of shoes in the United States while rewarding competitors that make more of their products overseas...