Cruz is a guy who's going to test one of my personal axioms. I have always believed that a sure-fire way to political oblivion for a national politician is to refuse to endorse your party's Presidential nominee.
I cannot think of a single Presidential contender for either major party who has ever failed to endorse his party's national ticket and succeeded as a viable contender for their party's nomination in the future. Not a single one of the Democrats for Nixon ever put forth a viable Presidential campaign again. Not a single Democrat who failed to endorse McGovern ever made any progress in getting support for their Presidential campaigns. Even Jimmy Carter said in 1972 that he would vote for McGovern, even if he wouldn't campaign with him. That's the weakest endorsement of a Presidential ticket ever by a guy who would later go on to be his party's nominee.
The GOP is no different. All of the Republicans who refused to support Goldwater never got anywhere, and that includes Nelson Rockefeller and George Romney. Richard Nixon was the 1968 Republican nominee in no small part because he endorsed Goldwater and actively campaigned for him. There's a reason the GOP gangs up against Ron Paul and why Pat Buchanan is persona non grata in Republican circles.
I think Cruz has come to this conclusion; he has to at least nominally endorse Trump in order to be viable in 2020. Cruz has been spurred in no small measure by the more likable Mike Pence moving into the role as a Conservative Fave for the future, and getting credit for taking shrapnel for Trump and helping other conservative Republicans win. Pence knows how to make friends. Perhaps Ted Cruz finally came to the conclusion that, at least in Republican circles, he had to stop making enemies.
That might be true...if he endorsed Trump at the RNC it would've been maybe viewed as a gracious defeat. Now it's just running late to catch the train and he'll be stuck in the back of the caboose for the rest of his career.
Cruz came to his senses when he realized that Mike Pence was about to be the new leader of the "True Conservatives". This would have put the unpopular Cruz out of the role of the Tea Party Express Chief Engineer.
The GOP Establishment and the Movement Conservatives have no use for Trump, as Trump engineered a hostile takeover of the GOP's Presidential Nomination Division. These factions probably cut Cruz a bit of slack given the insults dealt him by Trump. (I must admit that the linking of Cruz's father to the JFK Assasination was the MOST over-the-top thing Trump ever said.) Endorsing Trump now, I believe, made it right with these groups for Cruz; he's not disqualified for 2020.
I also think Cruz endorsed Trump because of Marco Rubio. Rubio, who had said he was retiring, re-entered Florida's Senate Race, and is favored for re-election. Cruz had supplanted Rubio as the GOP's leading Hispanic politician, but now, Rubio re-enters that competition, and the GOP very much needs diversity in its lineup. If he was seen as a ticket-bolter, Cruz would not be in a good position for 2020, and Rubio might be seen as a viable alternative.
