Sen. Mark Warner’s raspy voice was full of tightly-controlled anger last Thursday as he spoke to reporters on a media conference call about the breach of the U.S. Capitol that had occurred the day before.

“Why were we not prepared?” he said. “We were so under-resourced and underserved. It was outrageous … More people were arrested when the disability community came and tried to visit offices than these thousands of thugs who breached the Capitol … They clubbed more people in Lafayette Square so Trump could hold up a Bible.”

Warner had just come back from a 30-minute walk around the halls of Congress to look at the damage—windows broken, debris on the floors of the House and Senate—and to reflect on the injuries to Capitol law enforcement officers, and he was adamant that there would be a full investigation of the incident “to make sure this never happens again.”

“We’re going to make sure all these individuals are arrested and prosecuted,” he said. “If you could see the destru...