David Cameron and Jeremy Corbyn in May. Cameron has said he’ll step down as Prime Minister, while a huge majority of Labour M.P.s voted to pass a motion of no-confidence in Corbyn. Photograph by Stefan Wermuth / WPA Pool / Getty

Having started out as a drama and turned into a tragedy, the Brexit story line has now descended into farce. On a day when the governor of the Bank of England indicated that he and his colleagues would have to take emergency action to protect the British economy from the disastrous results of last week’s vote, Boris Johnson, the mop-topped Tory cheerleader for the Leave campaign, took to a podium at St. Ermin’s Hotel, in Westminster, and said, “This is not a time to quail; it is not a crisis, nor should we see it as an excuse for wobbling or self-doubt.”

Fighting words, it would seem. But then Johnson, the former mayor of London, announced that he wouldn’t be running for the leadership of the Conservative Party, and the keys to 10 Downing Street, in the fall, after Prime Minister David Cameron steps down, as many observers had expected. “My role will be to give every possible support to the next Conservative administration,” he said. “To make sure that we properly fulfill the mandate of the people that was delivered at the referendum, and to champion the agenda I believe in.”

I won’t go too deeply into the machinations that led to Johnson’s decision (my colleague Anthony Lane has more), but it appears that the opportunistic Old Etonian, who only joined the Leave campaign in February, lost his stomach for the fight after a fellow-Brexiteer, Education Minister Michael Gove, decided to run. For Johnson, who openly styles himself after Winston Churchill (he published an admiring book on him a few years ago), it was a stunning and humiliating withdrawal.

“He’s ripped the party apart. He’s created the greatest constitutional crisis of modern times. He’s knocked billions off the value of the nation’s savings,” Michael Heseltine, a former Conservative minister who is pro-E.U., told the BBC. “He’s like a general that led his army to the sound of guns, and at the sight of the battlefield abandoned the field,” he added. “I have never seen so contemptible and irresponsible a situation.... He must live with the shame of what he’s done.”

Heseltine’s words were well chosen. It’s doubtful, however, whether Johnson or the other politicians who led Britain into this situation feel any shame. Prime Minister David Cameron, another Old Etonian and the man who called the Brexit vote, is serving out his notice as a lame duck, saying that the country has to accept the referendum result. Jeremy Corbyn, the soft-spoken Islington leftist who occupies the office of the Labour Party leader without doing much that could be described as leading, is clinging on despite the fact that most of his colleagues in Labour’s shadow cabinet have resigned, and a huge majority of its M.P.s voted to pass a motion of no-confidence in him.

In the U.K.’s political system, if the heads of the government and the main opposition party don’t provide guidance, nobody else is in a position to do so. Tim Farron, the leader of the country’s third mainstream party, the Liberal Democrats, is a little-known M.P. from the Lake District who only got the job last year. Setting aside the Green Party, the Ulster Unionists, and nationalist parties from Scotland, Wales, and Northern Ireland, some of which have impressive figures at their helms, the country’s only sizable political organization with tested leadership is the anti-immigrant, anti-E.U. U.K. Independence Party. Its leader, Nigel Farage, has been taking a victory lap that included a jaunt to Brussels, where he serves as a Euro-bashing European M.P., to taunt his fellow elected officials.

In short, the United Kingdom is suffering a gaping leadership vacuum at a time when the nation’s very future is at stake. The current generation of political leaders is the weakest the country has seen in decades, perhaps even in a century or more. (Some would make a case for Neville Chamberlain, the architect of appeasement, or Sir Anthony Eden, whose premiership was destroyed by the Suez Crisis.)

Although Johnson has dropped out of the Conservative Party contest, this doesn’t mean that its Brexiteers are in retreat. All five of the candidates who have said that they will contend have made it patently clear that they now support Britain leaving the E.U., even though two of them—Theresa May, the Home Secretary, and Stephen Crabb, the minister for work and pensions—both supported the Remain campaign. “Brexit means Brexit,” May, whom the bookmakers quickly installed as the strong favorite, said on Thursday. “There must be no attempts to remain inside the E.U., no attempts to rejoin it through the back door, and no second referendum.” Crabb echoed these sentiments, saying, “The result was for the U.K. to leave the European Union. There can be no stepping back from that.”

The Conservatives’ abandonment of any effort to find a solution that could preserve Britain’s status within the E.U. leaves it to the opposition parties to take up the fight. As I noted at the start of the week, the cause is far from lost. But the events of the past seventy-two hours have been discouraging.

Corbyn, who remains the Labour leader in name, at least, can’t be expected to play a constructive role. He hails from a section of his party that has long regarded the E.U. as a capitalist plot. In the 1975 referendum on whether Britain should stay in the European Common Market (a forerunner to the European Union), he voted no. During the Brexit campaign, Corbyn was officially on the Remain side, but he showed little enthusiasm in making the case, and, like Cameron, he failed to persuade many of his party’s traditional voters to stay in the E.U.

Even if Corbyn is ousted, which will probably take a vote of the party’s entire membership, it isn’t clear who, if anyone, has the gumption and ability to lead Labour back toward the center ground, where it could conceivably defeat the Conservatives. As yet, none of the candidates who lost out to Corbyn in last year’s leadership election has indicated a willingness to challenge him again. Suggestions that David Miliband, a former Foreign Secretary, who lost the Labour leadership race in 2010 to his brother, Ed, might return to the U.K. from his current post running the International Rescue Committee, seem a bit fanciful. David Miliband is closely associated in voters’ minds with former Prime Minister Tony Blair, who is, partly because of his lucrative business dealings since leaving office, now extremely unpopular at the grassroots of the Labour Party.

There is some vague talk, in the tea rooms at Westminster, that the current crisis could lead to a lasting realignment of British politics. Under one scenario that is being discussed, Labour would split in two, with Corbyn and his allies leading an avowedly left-wing party, and centrists forming a new party that could reach an electoral pact with the Liberal Democrats. Such an outcome would represent a reincarnation of the Lib-Lab pact, which Herbert Gladstone and Ramsay MacDonald agreed upon more than a century ago.

That’s an intriguing prospect, but even if it were to happen it would probably take a while. For now, there is more urgent business to deal with. Britain desperately needs a leader, or a group of leaders from all the major parties, who will level with its people, telling them they have made a terrible mistake and offering a way out of the morass that the country has plunged into. Unless the Leave vote is reversed, the U.K. could well be headed for a future of isolation, disinvestment, and, quite possibly, breakup.

Despite the fact that more than four million people have signed an online petition calling for a second referendum, there is little sign of an organized effort at Westminster to satisfy this demand. So far, all we have seen is a parliamentary motion from two backbench M.P.s—one a member of the Labour Party and the other from Plaid Cymru, the Welsh nationalist party—that calls for the terms of Britain’s exit from the E.U. to be put to a national vote. If a more organized effort doesn’t emerge soon, history won’t treat this generation of British politicians kindly.