Yet the incoming prime minister believes he can, in such short order, secure meaningful changes to Theresa May’s deal, including in the “backstop,” an insurance policy to preserve an open border between the Irish Republic (remains in the European Union) and Northern Ireland (which leaves with Brexit). The backstop has enraged hard-line Brexiteers, who see it as a Trojan horse for keeping Britain in the customs union forever.

The Brexit question is also an Irish question. The peace agreement of 1998 yielded an open border. It’s a United Kingdom question. Why should a pro-European Scotland not favor independence over association with England?

It’s a Boris question. “Brexit means Brexit” is all Theresa May was able to muster. Is Johnson prepared to lay out why he actually believes in this folly?

Does he really want to be Trump’s poodle begging for some trade accord to offset Brexit’s cost to British commerce? Does he really want to cozy up to an American president who says he could, if he chose, wipe Afghanistan “off the face of the earth,” killing “10 million people”; portrays himself as a potential mediator in the Kashmir conflict with an outright lie; and resorts to a racist outburst repudiated by the German chancellor?

Or will Johnson, at the last, listen to reason? Brexit has proved undeliverable because it is. As John Major, the former prime minister, put it, Johnson “must choose whether to be the spokesman for an ultra-Brexit faction, or the servant of the nation he leads. He cannot be both.”

Johnson has many enemies, a paper-thin parliamentary majority, and the tightest of deadlines. His chances of getting a new deal through Parliament by October 31, or actually propelling Britain over the cliff of a no-deal Brexit, are slim to nonexistent.

So what then? He can call an election, but a Tory victory looks unlikely with the electorate split between Nigel Farage’s jingoistic Brexit Party, Jeremy Corbyn’s awful Labour Party, the resurgent pro-Europe Liberal Democrats and Johnson’s Tories. It would, in any event, be a leave-or-remain election, so why not call a second referendum? After three years of inconclusive chaos, with all Johnson’s lies in 2016 now exposed, Britons deserve a chance to say if they really want to leave.