With all the tumult of the last few weeks, I’m trying to take some bit of a break this weekend to keep charged for the next three months. But here’s one question I’m pondering and which I haven’t seen a good answer to. When Paul Ryan and John McCain started criticizing Trump over the Khan family affair, he tried to overawe them with the threat of not endorsing them in their primaries. I doubt either particularly cared for themselves. But for the party brass that was clearly a bridge too far. Would he go to war with every member of Congress who didn’t toe the line? The bigger threat was his gratuitous insults to Sen. Kelly Ayotte of New Hampshire, who’s in the fight of her political life and looks increasingly likely to lose.

Donald Trump is all about domination. And the thought of being dominated himself, humiliated is unbearable. And yet there he was on a stage in Wisconsin reading off endorsements of all three, much as we remember American hostages in Lebanon in the 1980s reading off captors’ messages. He caved and he caved hard.

So what happened? Some have suggested that Trump realized that Ryan was going to win easily and wanted to get out in front of that embarrassment. More persuasive to me though is the suggestion that he was given an ultimatum of some sort. The most logical one would be for the RNC to withdraw its money and personnel from supporting Trump. That would be particularly devastating for Trump. Usually it’s the party and congressional candidates that have to rely on the money and inertial force of the presidential campaign, which has the fullest coffers and best people in the field. It’s always a coordinated effort between presidential candidate and party. But in this case, the balance is entirely different. Even though Trump now seems to be raising competitive money, he barely has a campaign in the field to speak of. And that’s simply not something that can be stood up on a dime. No matter how much money you have that takes time.

But who would give that ultimatum? Reince Priebus? It seems off. And would the ultimatum even be credible? In most campaigns the obvious answer would be the campaign chairman, a top advisor or a group of major donors who would deliver such a message. But we’ve seen that those folks have zero control over him. Another consideration is Trump’s children. They seem to be the only ones who can shift his direction with other than threats. Did they get into the mix?

My final thought is that as much as Trump needs to dominate and be praised, he underwent a lifetime’s worth of humiliation in the early 90s when his whole empire appeared to be cratering and he hovered on the edge of personal bankruptcy. At least as a younger man, he was able to do what he needed to stave off ego annihilation.

I don’t have an answer for his one. But if we know Trump, this was an uncharacteristic submission. I’ve yet to see any persuasive account of just what that unseen force was.