The Liberal Democrats and SNP have tabled a one-page bill that would give Boris Johnson the December election he craves – but on Monday 9 December rather than Thursday 12 December.

It would put aside the Fixed Term Parliaments Act for one election only, and includes a clause that would immediately undo the move to an election if the European Union offers only a short extension to the Brexit process. Although both the Liberal Democrats and SNP support extending the franchise to voters aged 16 to 18, and the SNP have already done so for devolved elections in Scotland, they would not support efforts to do so in this instance, as it would delay the passage of the bill, pushing back the date of an election, and, in any case, the policy would require a longer period of consultation and implementation to be meaningfully implemented in England and Wales anyway.

Why so much fuss over a few days? Well, there are two fears that Johnson’s opponents have about a 12 December election. The first is that because it happens so late in the year, Parliament wouldn’t return this side of 2019, and it risks a no-deal by accident because of the time taken to swear in MPs, elect a new Speaker and their deputies, hold the state opening and so on. Holding an election just a few days earlier means that Parliament could return in the last week of December rather than mid-January. That’s the argument that Labour MPs with the ear of Jeremy Corbyn are making to dissuade him from an election.

But the extra days also matter before an election, because they cut into legislative time that could be used to ratify the terms of the United Kingdom’s exit from the European Union. While there is division in this Parliament about the future relationship after we leave, there is a narrow majority to support the terms of exit more broadly. The bulk of the Liberal Democrat parliamentary party and the SNP leadership now believe that if this Parliament continues in place, it will ratify the deal. Perhaps Johnson will have to swallow some minor defeats in making assurances about the future trade agreement, but in practice, with an election looming, enough of the small group of Labour MPs considering voting for the deal at second reading will do so to make it pass.

Will the Conservatives accept it? Their line to take on it on today’s news programmes is that the move is a “stunt” by the Liberal Democrats and the SNP. But their line to take on last week’s news programmes was that Brexit would be done, 100 per cent, by 31 October.

If the Conservatives want an election in which they can say that they are the only party who can “save Brexit” this is their best chance of getting one. And for Remainers, it represents their last realistic hope of stopping Brexit in its tracks.