Nicola Sturgeon and Jo Swinson.

Hugo Dixon, The Independent

Boris Johnson’s proposal to hold an election on December 12 seems set to be defeated in the Commons. But Jo Swinson’s and Nicola Sturgeon’s plan to hold one on December 9 may have legs – particularly if the prime minister jumps on board and supports it.

This would be unfortunate. It would be better to push for a People’s Vote before an election.

The Lib Dem and SNP leaders say their election plan is the best way to stop a “no-deal” Brexit. But they are overstating their case.

There are at least three ways that we could still crash out of the EU – even now that the bloc has delayed Brexit until 31 January.

First, if Johnson loses the election, he doesn’t have to resign immediately unless another party gets a majority – and the chance of that happening is slim. So he could wait until parliament meets again, at which point he still only has to resign if there is a “clear alternative”.

It’s also up to the prime minister to advise the Queen when to bring back parliament after an election. Normally, it’s on a Wednesday. So, with Christmas coming, the prime minister could delay the first meeting of parliament until 8 January. And if he wanted to postpone it even longer, there’s no obvious legal route to stop him. There could then be endless wrangling about who should take over and, before you knew it, 31 January would be upon us and we could crash out.

Second, if Johnson hangs on as prime minister after an election without a solid majority, he could put a gun to MPs’ heads – saying they either have to support his rotten deal unchanged, or there’ll be no deal. If neither side backed down in this game of chicken, we’d crash out on 31 January.

Finally, the no-deal option won’t be off the table even if Johnson wins the election and gets MPs to back his deal. The prime minister’s withdrawal agreement only postpones our departure from the EU’s single market until the end of next year. Johnson says he won’t extend this “transition”.

So, if he doesn’t manage to agree a trade deal with the bloc by the end of next year, which would be extraordinarily fast, we’ll be staring at another cliff edge. Again, crashing out is a real risk – especially after Kwasi Kwarteng, the business minister, revealed that “no deal” would not be taken off the table.

The Lib Dem/SNP legislation could be altered to fix the first of these problems. It could determine not just the date of the election, but also state that parliament should be recalled before Christmas. But it can’t deal with the other two.

If there was no viable alternative, it might still be sensible to go with the Swinson/Sturgeon plan. But there is one: ask the people in a final say referendum whether they want Johnson’s deal or would prefer to stay in the EU. That’s a far better way of deciding what happens on Brexit than muddling it up with who runs the country.

Pessimists will say there isn’t a majority in this parliament for a People’s Vote. But the more MPs scrutinise the prime minister’s pig of a deal, the more they will see its flaws. Tory MPs who were kicked out of the party increasingly realise the danger of a “no-deal” Brexit in 2020. Labour MPs who were tempted by Johnson’s commitment to uphold workers’ rights should see he is double-crossing them after a government document boasting how it could wriggle out of its promises was leaked to the FT.

Such MPs may well now conclude that a Final Say referendum is the best way to resolve the crisis. It would be a mistake to go for an election before having one last push to get a People’s Vote through this parliament.