When Lee brought up his bill in the committee hearing, he wasn’t sure if he’d have Cruz’s support. But he certainly didn’t anticipate what came next.

Cruz attacked the bill as dangerous and politically poisonous. He said it would lead to more than 7,000 federal prisoners let out on the street. “I for one, at a time when police officers across this country are under assault right now, being vilified right now, when we’re seeing violent crime spiking in our cities across the country, I think it would be a serious mistake for the Senate to pass legislation providing for 7,082 criminals to be released early,” he said. The bill, he claimed, “could result in more violent criminals being let out on the streets, and potentially more lives being lost.”

Cruz went on to warn his fellow senators that if they voted for the bill, they would imperil their careers. “We know to an absolute certainty that an unfortunately high percentage of those offenders will go and commit subsequent crimes,” he said. “And every one of us who votes to release violent criminals from prison prior to the expiration of their sentence can fully expect to be held accountable by our constituents.” Essentially, Cruz was saying that the legislation would let dangerous people out of prison, they would commit more crimes, and the senators would be subject to Willie Horton-style attack ads.

Lee, who was sitting right next to Cruz, could not believe what he was hearing. The bill, he responded, wouldn’t actually release any violent criminals from prison, and its sentence reduction for gun crimes was to reduce the minimum for felons caught with guns or ammunition from 15 years to 10 years—a provision that had once sent a man to prison for 15 years when he picked up a stray bullet in order to clean a carpet. “It is simply incorrect to say that this suddenly releases a bunch of violent criminals. It is tougher on violent offenders,” Lee sputtered. “That statement is inaccurate…. We’re not letting out violent offenders. That is false.”

Lee’s communications director, Conn Carroll, confirmed to me that Lee and his staff had no advance warning that Cruz was planning to brutally attack—and, in Lee’s view, misrepresent—his friend’s bill. “Going into that hearing, we definitely thought it was in the realm of possibility he would come out against it, just not with that kind of colorful language,” Carroll told me. The bill made it out of committee that day, but now it appears to be in trouble, with several other Republican senators taking Cruz’s line against it at a Senate lunch last week.

Today, Lee has conspicuously joined every other sitting senator in declining to endorse Cruz’s presidential run. And while Lee and Cruz are still friends, the episode vividly illustrates Cruz’s talent for irritating other senators.