ESPN, under intense pressure again in the hypercharged terrain of social media, elicited a rebuke from a White House official on Wednesday in response to a series of tweets posted by a “SportsCenter” host.

Jemele Hill, who co-hosts the 6 p.m. “SportsCenter” program, called President Trump a white supremacist on Twitter on Monday, adding: “Trump is the most ignorant, offensive president of my lifetime. His rise is a direct result of white supremacy. Period.”

Sarah Huckabee Sanders, the White House press secretary, said the comments were a “fireable offense.”