Kari Lake, the leading Republican candidate for Senate in Arizona, delivered a speech in front of a Confederate flag at a Trump-themed merchandise store in Show Low, Ariz., last week.

Footage of the speech, which was obtained by The New York Times, showed Ms. Lake on May 31 repeating lies about the 2020 election’s having been stolen from former President Donald J. Trump as she stood in front of a Confederate battle standard hanging in the store. The flag has become the one most associated with the Confederacy in the modern era.