Bernie Sanders had a hard time of it in Houston.

In a particularly striking moment, host Aimee Allison asked Sanders what he would do to fight white-supremacist violence. In response, Sanders launched into a familiar anecdote that — perhaps precisely because of its familiarity — seemed to crash and burn.

“I know I date myself a little bit here, but I actually was at the March on Washington with Dr. [Martin Luther] King back in 1963,” Sanders began, as audible groans and jeers broke out at the auditorium at Texas Southern University. One person apparently shouted, “We know!”