And now for perhaps the most interesting and dramatic question of the 2016 Republican Convention: Ted Cruz’ speech, and what it will contain.

We know that Cruz is not going to explicitly endorse Donald Trump. That has been reported by numerous sources; when it was announced that Cruz would speak at the convention, the Trump camp called the meeting preceding that announcement a “mending of fences.” But both sides reported that no pledge of an endorsement was demanded nor given. So Cruz would be bound only by his earlier pledge to support the GOP nominee, a pledge no reasonable person would expect him to be bound by after Trump had the National Enquirer spread lies about his supposed philandering, attacked his wife and suggested that his father had a hand in the JFK assassination.

Trump should have been able to get Cruz’ endorsement, but those stupid mistakes preclude it. In a previous time he’d be more likely to be facing Cruz with a pistol at dawn as a result of those actions; things are more civilized now, but there will not be an endorsement.

At National Review and Hot Air, there are a couple of pieces talking about the historical parallels to Cruz’ speech tonight; namely, Ronald Reagan’s speech to the RNC in 1976 and Pat Buchanan’s speech at the 1992 convention. Cruz certainly sees himself as a Reaganesque figure, though as a communicator and a figure with wide political appeal it’s fair to say that he might be a work in progress at best. That would make him more of a Buchanan, who generated a passionate following in 1992 but not a particularly broad one.

Interestingly, though, that both Reagan in 1976 and Buchanan in 1992 gave endorsements during their addresses to the convention. Reagan endorsed Ford (UPDATE: Scratch that, because Reagan didn’t actually endorse Ford), while giving a speech that was received in the hall and elsewhere in the spirit that perhaps the party had chosen the wrong nominee and would remedy that mistake four years later, and Buchanan endorsed George H. W. Bush in 1992. A snippet of that speech, which turned out to be more troublesome for Bush than had Buchanan not made an endorsement…

But tonight I want to talk to the 3 million Americans who voted for me. I will never forget you, nor the great honor you have done me. But I do believe, deep in my heart, that the right place for us to be now–in this presidential campaign–is right beside George Bush. The party is our home; this party is where we belong. And don’t let anyone tell you any different.

Yes, we disagreed with President Bush, but we stand with him for freedom to choice religious schools, and we stand with him against the amoral idea that gay and lesbian couples should have the same standing in law as married men and women.

We stand with President Bush for right-to-life, and for voluntary prayer in the public schools, and against putting American women in combat. And we stand with President Bush in favor of the right of small towns and communities to control the raw sewage of pornography that pollutes our popular culture.

We stand with President Bush in favor of federal judges who interpret the law as written, and against Supreme Court justices who think they have a mandate to rewrite our Constitution.

My friends, this election is about much more than who gets what. It is about who we are. It is about what we believe. It is about what we stand for as Americans. There is a religious war going on in our country for the soul of America. It is a cultural war, as critical to the kind of nation we will one day be as was the Cold War itself. And in that struggle for the soul of America, Clinton & Clinton are on the other side, and George Bush is on our side. And so, we have to come home, and stand beside him.

It wouldn’t be a surprise to see Cruz revisit the spirit of that endorsement without actually making one for Trump. When Buchanan gave that speech, he was essentially pinning Bush to the wall on a host of issues the president had not been particularly aggressive in promoting, one reason why he’d had trouble inside the GOP in the first place – but many of those issues weren’t winners with the general electorate. Should Cruz do something similar, and declare that the Republican Party (rather than Trump per se) is the party of social conservatism and that conservatives must vote Republican to see such policies enacted, it would put Trump in a similar uncomfortable place. Much of the GOP platform is significantly rigid on the social conservative side, after all, but Trump hasn’t taken any steps to embrace that wing of the party and isn’t likely to put much political capital at risk to support that platform.

By making a case for social conservatism, Cruz can put himself in a position to use Trump’s failure to mobilize social conservatives as an argument for why Trump loses in November.

And there are a number of other issues and classes of issues where Cruz differs with Trump that can be similarly raised in the speech. Another example – judges. Cruz can attest that only the Republican Party can be expected or trusted to appoint constitutionalists to the Supreme Court and other seats on the federal bench, and even name a few who should be expected as nominees.

Cruz has one goal here, and it’s a selfish one – he’s setting the stage for 2020, and putting himself in a position to serve as the standard-bearer for the Republican Party after Trump loses in November. Or, should Trump win, Cruz is setting himself up as the opposition within the GOP and the conscience of the party which holds itself out as the home for conservatives – which could mean Cruz is a primary challenger to an unpopular President Trump in 2020. These things would be relatively simple to do if he was endorsing Trump as Reagan endorsed Ford in 1976 – if Cruz could make a case that Trump actually believes in conservative principles, he would then be the heroic selfless uniter of the party behind its nominee.

That he isn’t making the endorsement complicates things. Cruz could very clearly make a case that Trump is no conservative; that isn’t hard to do. But indicting the GOP nominee as unworthy in so many words is political poison – do that, and it’s your fault if Trump loses rather than Trump’s. And if Trump wins, you’d might as well start your own party, because there will be recriminations galore.

So it’s a very narrow tightrope Cruz will have to walk. He has to get across the message that he and his faction of the party are not satisfied with the nominee and he has to warn that the departure from principle Trump represents is a major mistake, but he has to do it without coming off as disloyal to the party.

If he pulls that off, this will be an historic speech, and potentially the kind of marker to his career representing his graduation from conservative gadfly to major political force. If he doesn’t, he risks putting himself in a political cul-de-sac that bars him from status as the future of the Republican Party going forward.