A couple of weeks ago, people boycotted Nordstrom for one reason: The department store sold Ivanka Trump products.

Now people are boycotting Nordstrom for another reason: The store said it would not sell her products.

These days, a shirt is not always just a shirt, and a store is not always just a store. Handbags, dresses and other ordinary items — and where they are bought — have become politicized, turning shopping decisions into acts of protest for the millions of people in pro- and anti-President Trump camps. Under Armour, L.L. Bean, T.J. Maxx and many other companies have already been pulled into a sort of ideological tug of war.

But perhaps no retailer has been in the hot seat like Nordstrom.

The “boycott Nordstrom” movement instantly changed political direction after the department store scrubbed Ms. Trump’s name from its site last week. Thousands of people lashed out at the retailer online. Even President Trump himself posted on Twitter that his daughter had been treated “unfairly.”