As the polls stand, Owen Smith may have little prospect of becoming Labour leader, but in the unlikely event that he does, he has cast himself, as of today, as the flag-carrier for a reconsideration of Brexit in the form of a second referendum or a general election. The voters, he says, should have the final say.

Smith is not, of course, the first to call for another referendum: such calls have been two-a-penny since 23 June, and a second referendum is a favourite mechanism among those who regret the result. But he is the first to actually campaign for office on such a pitch, presumably intending it to form a decisive demarcation line between himself and the party leader he is challenging, the seemingly reluctant remainer, Jeremy Corbyn.

The second referendum proposal is no more than wishful thinking on the part of thwarted remainers

If it were to become Labour policy, then it could perhaps be said that the opposition would be doing its job in presenting an alternative to the prime minister’s deceptively straightforward “Brexit means Brexit”. But his call for another vote muddies a lot of waters. The decision to invoke that famous article 50 and start the clock on the UK’s departure is receding ever further away.

Smith’s central argument is that people did not know what they were voting for when they supported leave, and should have the final say when the terms of the divorce are clear. That is as patronising as it is self-serving. Some Brexiters may have regretted their vote – as perhaps did some of their shocked leaders. But the people have voted. The majority, if small, was clear. We ridiculed the Irish for holding a second referendum to “get it right” the second time around. UK voters knew exactly what they were voting for. If our democracy is worth anything, that vote must stand.

The delay in invoking article 50 already threatens damaging uncertainty, both in UK politics and in our relations with the rest of the EU. Angela Merkel has been more indulgent than most of the prime minister’s desire not to act with haste. But even her patience has its limits, not least because both she and the French president face elections next year. If Brexit is indeed to mean Brexit, then the date needs to be fixed with some dispatch. The precise terms may indeed be subject to negotiation, but the fact of departure is not among them.

The second referendum proposal is no more than wishful thinking on the part of thwarted remainers. It has hovered over the result like a get-out clause and Owen Smith, unfortunately – and I say this as a remainer – has given the idea new life.

His other avenue towards a new vote, a general election, would be more promising in democratic terms, but could lead to even longer and more profound uncertainty. Were Labour not in such turmoil, it would make sense for the party to call for an early election on the grounds that Theresa May should seek her own mandate.

It looks unlikely now, but if there were an election, if Labour and the Liberal Democrats campaigned on a remain platform, and if they won – so many ifs – where would the constitutional advantage reside then? The result of a referendum would have to be weighed against the – more recent and contrary – result of a general election. It could go to the supreme court. Alas, the damage to the European Union and to the UK’s standing therein would have been done.