He was dining with friends when he encountered Joseph A. Califano Jr. — the former US secretary of health, education and welfare under President Jimmy Carter and domestic policy adviser to President Lyndon B. Johnson — and his wife, Hilary, who were having a quiet dinner.

Onlookers said Schumer was incensed that Hilary — the daughter of William S. Paley, the founder and chairman of CBS — had voted for Trump, even though her husband, Joseph, is a well-known Democrat.

One witness said of the restaurant rant, “They are a highly respected couple, and Schumer made a scene, yelling, ‘She voted for Trump!’ The Califanos left the restaurant, but Schumer followed them outside.” On the sidewalk, Schumer carried on with his fantastical filibuster: “ ‘How could you vote for Trump? He’s a liar!’ He kept repeating, ‘He’s a liar!’ ”