Yet if there are six reasons Cruz gives for embracing Trump, there are another five for why his endorsement is the most stunning about-face of any of the Republicans who once opposed the real-estate tycoon.

Words No Longer Matter

The examples at the start of this article are just a small sample of the vitriol exchanged between Cruz and Trump during the height of their primary battle. Yes, Trump exchanged insults with just about all of his Republican opponents, and many of them—like “Little Marco” Rubio—ended up endorsing him. But Cruz is now backing a man for the nation’s highest office that he considers to be a liar, a coward, and amoral. Those are charges you don’t just take back or minimize, and to do so reinforces the cynicism that many voters have about the political process.

Honor Thy Father?

Cruz had a pretty good reason for calling Trump all those things back in the spring: Trump ran an astonishingly dirty campaign against him! Just as he did for years with President Obama, Trump repeatedly floated a birther theory about Cruz and suggested he was ineligible for the presidency because he was born in Canada. He even threatened to sue Cruz over it. Then Trump turned on Cruz’s family. He tweeted unflattering pictures of Cruz’s wife and threatened to “spill the beans” on her (though he never hinted at what “the beans” entailed). Finally, Trump spread a rumor, based off a grainy photo in the National Enquirer, that Cruz’s father Rafael was involved in the Kennedy assassination—and he continued raising it the day after he accepted the Republican nomination for president. Cruz didn’t mention this in his Facebook post, presumably lumping all of these charges into the “significant areas of disagreement” that he acknowledged he has with Trump.

Brand Ruination

Cruz has worked diligently over the years to forge a political identity that can be summed up thusly: He is a conservative who fights on principle, whether or not that accords with the wishes of his party’s leadership. By bowing down to a man he has attacked so harshly, Cruz significantly dilutes that brand. As I wrote previously, Cruz is facing a potentially difficult primary battle in his reelection bid for the Senate in 2018, and he undoubtedly determined that he needed to make amends with the sizable contingent of Trump supporters in Texas—especially knowing that he can’t count on the support of party leaders he has long since alienated.

Polls showed Cruz’s support among Republicans dropped significantly when he refused to endorse Trump at the GOP convention in Cleveland. Yet conservatives, including some of Cruz’s top allies and former advisers, are already calling this decision just as self-serving as that one. As for whether Cruz’s political calculations help or hurt him if he runs for president again in 2020, it’s surely too early to say. Cruz now leaves Ohio Governor John Kasich as perhaps the most Trump prominent holdout who is eyeing another White House bid in four years.