The issue that Cruz is so angry about—the Ex-Im Bank—is not one that’s likely to move a lot of Republican votes. The bank helps U.S. businesses find markets overseas, but conservatives have targeted it as a prime example of corporate welfare and “crony capitalism.” Congress allowed the bank’s charter to expire at the end of June, but shortly before Cruz spoke, McConnell announced plans to allow supporters of the bank to attach an amendment reviving it to a three-year highway bill the Senate is going to pass next week. The majority leader had said publicly for weeks that the Ex-Im amendment vote would likely happen, but Cruz claimed that he had promised the opposite to Republicans in a private meeting earlier this summer.

“We now know that when the majority leader looks us in the eye and makes a commitment, he is willing to say things he knows are false,” Cruz said. To appease conservatives, McConnell said the Senate would also hold a vote on a full repeal of Obamacare—an offer that Cruz treated as an insult. “It will be an exercise in meaningless political theater,” he said. “An empty show vote—that’s a good way of distracting from whats really going on.”

Accusing another senator of lying on the Senate floor is not just rare—it runs counter to the Senate’s rules:

No Senator in debate shall, directly or indirectly, by any form of words impute to another Senator or to other Senators any conduct or motive unworthy or unbecoming a Senator.

Cruz’s rant against his party leader was all the more notable because he has repeatedly refused to denounce Donald Trump’s critique of immigrants, or his later attack on John McCain, because, Cruz told Chuck Todd on Meet the Press: “I’m not interested in Republican-on-Republican violence.” That principled stand appears to have given way to Cruz’s desire for the votes that Trump is now hogging.

For his part, McConnell ignored Cruz’s diatribe and pointedly did not respond to it when he spoke on the Senate floor later in the day. (In truth, he was probably more offended at Cruz’s other accusation—that he was running the chamber in the same way as his Democratic predecessor and nemesis, Harry Reid, despite his promises of change.) McConnell surely saw Cruz’s outburst for what it was: A desperate attention-grab by a candidate sitting at 4 percent in the last two presidential polls, whose bad-boy status as the GOP’s ultimate conservative outsider has been eclipsed by the antics of The Donald.

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