The shocking result of the "Brexit" referendum, with Britain leaving the European Union, has widely been taken as Good News for Donald Trump. He was happy to say so himself, and to attempt to take credit somehow for the referendum's success. And people have been panicking about the danger that Trump's campaign could beat the conventional wisdom just as the British "Leave" campaign did. That danger is probably overrated, as Jamelle Bouie points out: the UK is much whiter than the US, so the angry white vote doesn't carry as far here any more, and we should remember that the Brexit result wasn't really a surprise: "Leave" and "Remain" had been polling neck-and-neck down to the wire, so the 52-48 result wasn't unlikely. But Trump, who led the Republican primary polls wire to wire, is clearly behind in the general-election polls. On the other hand, it's easy to see Trump and the Brexiteers as part of a wider movement: angry nativist populists, hostile to policy experts and welcoming to xenophobes and racists.  That movement won't meet with the same success everywhere, but it's real.

I want to move past the obvious similarities to look at two more important comparisons. Both the American and British situations feature 1) the country's major conservative party tearing itself apart, mostly because of 2) a long history of campaign promises that were never meant to be kept, because the people making them considered them impossible. Let's take these one at a time.

First of all, the Brexit is deeply tied to  a civil war inside the UK's Conservative Party. The "Remain" and "Leave" campaigns were led by rival Tory politicians: the Prime Minister, David Cameron, led the campaign to stay in the EU and Boris Johnson, who has long been gunning for Cameron's job, led the campaign to quit the EU. That would be bad enough, but it's worse: the leaders of BOTH campaigns have destroyed their political fortunes. Cameron resigned his Prime Ministership the day after losing the vote. Today, Boris Johnson turned his expected announcement of his campaign for Prime Minister into a surprise resignation speech. He won't be running for PM, and is resigning his seat. It's like House of Cards, but with lots of twists and drama.

The Brexit vote itself was meant to ward off Tory civil war, with Cameron throwing the referendum out as a sop to fend off both the anti-immigrant fourth or fifth party called the UK Indepence Party, and the Brexiteer faction of his Cameron's own party ... essentially to shut Boris Johnson up. So, that plan has gone as badly as it could go: UKIP and its loathsome chief, Nigel  Farage, have now been empowered, Cameron has lost his premiership, and Johnson has immediately fallen on the sword he used to decapitate Cameron. How did it go so wrong?

It went so wrong because the Brexit itself was a poison pill: easy to campaign for, but a disaster to put into practice. Once the Leave side had won, and Cameron had chosen to resign without triggering the exit (as opposed to triggering the exit and then resigning, which only a fool would have counted on him doing), Johnson and the other Leave leaders were stuck. The Prime Minister who actually triggers the Brexit, who begins the formal process of withdrawal, will be on the hook both for the bad effects that follow, especially the flight of business and banking from London to other European cities, and for the drawbacks of whatever deal the UK hammers out with the remaining European powers.

Here's the thing: Boris Johnson knows the consequences of the Brexit will be bad, and he knows that the deal with Europe won't deliver what he promised. London has become the financial capital of Europe under the current deal, and that becomes impossible if the UK leaves. An enormous amount of business WILL leave the UK, and take jobs with it. Meanwhile, the EU will never allow a country access to its market without both paying dues and (more importantly) allowing free immigration from the rest of the EU. Countries like Switzerland, which have side deals with the EU, have to allow free immigration, so the end to immigration that the Brexiteers promised will never happen without losing access to all that sweet tariff-free trade. BoJo knows these things.

But BoJo and the other Brexiteers publicly denied all of these things. They denounced the (true and totally common-sense) warnings that the Brexit would lose British jobs as "scaremongering." And BoJo began making noises after the vote about how the UK could stay part of the European market, etc. etc. etc. Except it can't without, you know, staying in. So Johnson, who has made his entire career on basking the EU, had no way forward. The backstabbing finale, in which Johnson's deputy from the Leave campaign put the knife to his prospects, was just the inevitable ending.

Johnson has been living for years off a popular (and populist) movement which he knows would be disastrous but which he didn't really think could succeed. It's very obviously that he had no plan for what to do when he won. He didn't plan for the Brexit because he never expected not necessarily even wanted it to happen. It was just a convenient set of talking points to rally a populist base against the party insiders, splitting populist Tories from the party's pro-business establishment, to advance BoJo's career. He was making a set of fairy tale promises.

Boris Johnson has campaigned for years, as both politician and journalist, on a "Let's All Go to Narnia" platform. It's not practical in any way, but it strikes a deep chord with voters and gets them passionately enthusiastic. Even better, it forces Boris's political opponents into the unenviable position of arguing against Narnia, and sounding like passionless, pedantic jerks. No one likes the Anti-Narnia guy. And Boris never had to worry about what he proposed coming true, because it was so far from being possible.

Then one day, Boris Johnson found himself hip-deep in snow, staring dumbfounded at a lamp post. What to do, but crawl back into your uncle's wardrobe and hide?

Here in America, we're seeing a parallel breakup of the Republican coalition, as its populist wing breaks away from its traditional business-oriented policies. Everything Trump promises the crowds would be catastrophic for American business. But the other Republicans aren't in much position to debunk Trump, because they have been cynically feeding Trump's own fairy-tale promises to their base for years now. Trump's border wall is not Trump's idea. Trump has no policy ideas of his own. The border wall with Mexico has been a fairy-tale proposal that various Republicans have hawked during primaries and off-year elections for years. (Sometimes they have called the wall a "security fence" in order to sound smarter, and make the totally unworkable proposal sound like something practical.) I've been hearing about that "build a wall" plan since at least the 90s. No one who made that promise ever had to worry about it happening. And if Trump actually won, he would quickly discover that building the wall would be ruinously expensive and pointless.

Here's the Republicans' real problem. They have a whole batch of fairy tale policies that they've been pushing to their voters for years now. (The Democrats also have some pie-in-the-sky plans that they don't think are achievable at the moment, but the actually think those things could work if put into place. And they have a habit of only campaigning on what they think they can get done in the next few years.) Clinton's policies are things she that she thinks could get through Congress and will work if they do.

"Repealing Obamacare" is a classic fairy-tale promise. It excites the Republican base like no one's business. But the Republicans also know that they can't actually do it, and that doing it would be a disaster. Throwing people off their health insurance is not something you do in office. Likewise, actually banning abortion would be the ruin of the party that does it for decades afterward. That doesn't stop them from campaigning on these fairy-tale promises. In fact, they campaign on them so hard because they know they can't make these things happen. But if they did, it would be a disaster. This is red meat you feed the rubes. The problem comes, not just for a political party but for a whole nation, when the rubes expect you to do what you've promised them.