Who betrayed Brexit? That’s the question both Labour and the Conservatives will surely put to the country at the next election, whenever it is. One Tory minister recently sketched out three possible futures to me: the first, a catastrophic Brexit without a deal; the second, a deal that breaks many of the pledges made initially by Vote Leave and then by Theresa May; and, last of all, a deal in which the United Kingdom remains in permanent transition until either the Tory party’s civil war resolves itself or new technology solves the Irish border puzzle. A long time indeed, in other words.

What connects all three of these outcomes is that the British people voted for none of them. But the Conservatives don’t intend to hand over the reins of government to Jeremy Corbyn without a fight, so an explanation for what went wrong will have to be found.

Some Tory MPs believe they have a perfect scapegoat in May: the Prime Minister’s last act will be to sign a deal full of indefensible compromises before she is toppled, allowing a new leader to defeat Corbyn. Yet the same problems that have frustrated May are likely to persist into the era of Sajid Javid, Jeremy Hunt or whoever emerges as the next Tory leader: no parliamentary majority and a series of Brexit objectives that cannot be reconciled.

If not May, then who? The Conservatives can hardly blame David Cameron, because the party cheerfully fought one election supporting his call for a European referendum and another promising to uphold the result. They can’t blame the voters for signing up to a false prospectus, either – because they were the ones who were hawking it.

What the Tories can do is blame the opposition parties for voting against Brexit whenever possible in the Commons. To those who know Corbyn well, that seems ridiculous: he is an instinctive Eurosceptic who has shied away from any vote that could be portrayed as “stopping Brexit”. Talk to most of the organised Remain campaigns, and they will tell you that Corbyn is at best unenthusiastic about Britain’s membership of the EU, and at worst seeking to hasten Britain’s departure from it.

Expecting voters to follow an internal left-wing row, however, is bubble-think. As far as the electorate is concerned, by the time of the next election, Corbyn will have voted against most of the government’s Brexit bills, together with the overwhelming majority of his MPs.

Nearly everyone in Labour, from Corbyn’s inner circle to the most isolated of Corbynsceptic backbenchers, accepts that the only viable course of action will be to vote against whatever final deal the Prime Minister brings to the House.

That worries Labour MPs who represent marginal constituencies where people voted strongly for Leave. They understand the imperative to defeat the government but they fear that strategy might also come with a heavy price tag in the form of their seats. The strategy has implications for angry Europhiles, too. Those who dream of a pro-Remain backlash against Corbyn forget that the full might of the Conservative machine and its media allies will be reminding every voter that the opposition, more often than not, lined up with the forces of Remain rather than Leave.

May gave a preview of this line of attack on 18 July, in the final Prime Minister’s Questions before the summer recess, when she castigated Corbyn for failing to back her Brexit plan and for not ruling out supporting another referendum.

The Labour leader, however, has his own attack lines on the subject of Brexit betrayals. As his office likes to do, it previewed one of these in a Facebook advert. The Tories had sold out on the promise of “taking back control”, it claimed. Voters could wrestle back that control from private companies when Labour fulfilled its promise to nationalise the railways and utilities. Another version of the betrayal narrative was rolled out in Corbyn’s speech on 24 July, when he accused the Conservatives of not doing enough to maximise the opportunities for British manufacturers created by “the one benefit to them that Brexit has already brought – a more competitive pound”.

As one Corbyn aide puts it, the choice for voters will be between “different versions of betrayal”. The long-term repercussion will be a political debate that is uglier and characterised by deepening mistrust. In the short term, however, neither main party feels it can risk being seen as responsible for letting down Brexit voters; both sides need to pin the blame on the other.

The problem for the Conservatives is that this message flows more naturally from Corbyn’s lips than from their own. Labour didn’t win the 2017 general election and voters tend to look poorly on governments that blame their opponents for their problems. Nor will Corbyn hesitate to strike a more stridently pro-Leave line if he feels he needs to do so to win.

If the Conservatives can’t think of a way to make a disastrous Brexit outcome palatable to the electorate, there is one remaining course. Insist, come what may, that the talks have been a success.

To do that the Tories will need a leader who is well-known to the public, has demonstrated his or her commitment to Brexit and is trusted by Leave voters (even if no one else sees the appeal).

The good news for the Conservatives is that such a politician exists. The bad news is that his name is Boris Johnson, and most Tory MPs detest him. Yet they might come to regard this as a price worth paying to avoid a still more undesirable Brexit future: one in which Corbyn resides in Downing Street.