When answers are in short supply, sometimes the best we can do is try to ask the right questions. Some of those dive into legal and constitutional arcana, as experts try to work out how Boris Johnson can climb out of the hole he has spent this last week digging ever deeper for himself. Now that the opposition parties have refused to accede to his cunning plan for an October election, and will next week see passed into law their demand that he seek an extension of Britain’s EU membership, he’s left with a series of unpalatable alternatives – from breaking the law to resignation to tabling a motion of no confidence in himself.

Still, even if it’s later rather than sooner, polling day is coming. So here goes with the three questions that will decide the next election and, with it, the fate of Brexit.

First, when? Given the procedural chicanery and willingness to trash established convention we’ve witnessed these last few days, nothing is certain, despite today’s move to block a poll before 1 November. What’s at stake here is the context in which the election will take place. Johnson’s preference has always been to face the voters before the exit deadline, lest he be cast as having failed in his “do or die” mission to leave by 31 October. This is the prize the opposition has agreed to deny him, forcing him, they hope, to confront the electorate in November as a failure, guilty of either treachery or incompetence. Their hope is that Johnson’s inability to take Britain out of the EU will pump new air into the Brexit party balloon, thereby splitting the leave vote that Johnson had bet everything on uniting around himself.

But there’s risk here too. Some Labour MPs fear that fury among pro-Brexit voters will be at its peak in the immediate aftermath of 31 October, as those voters realise they’ve been cheated of Brexit once again, that London / the elite / Labour / remainers have consigned them to another spell in European “purgatory”. In this view, leavers will rally to Johnson’s cry of treachery, seeing him as their defiant, relentless tribune. They won’t be diverted to Nigel Farage because Johnson will be supplying the same populist drug, as illustrated by his slash-and-burn antics this week. According to one former cabinet minister, “He has decided to beat the Brexit party by being the Brexit party.”

Second question: what cuts through? Or, put another way, what’s the signal amid all this noise? For those watching closely, glued to Twitter or following rolling news, the last week has been extraordinary. If they’re not sharing pictures of a languid Jacob Rees-Mogg sprawled on the Commons benches, expressing contempt for parliament in physical form, they’ve been gasping at the gall of a Tory PM purging his party of some of its grandest figures, two ex-chancellors included, and at the remarkable feat of a new prime minister losing his first four Commons votes. But how much of that gets through to the vast bulk of voters, who might catch the odd bit of news on TV, a few headlines on commercial music radio or via Facebook? While your Twitter feed was spitting outraged noise at the culling of Nicholas Soames, it’s possible that the signal was “PM fights hard for Brexit.”

An example came on Thursday night, when Johnson delivered a rambling speech in front of a phalanx of police cadets, wilting in the sun. In Westminster world, following the entire event live, the focus was on the sinister, Trumpian use of cops as props and on the PM’s bizarre incoherence. But the five-second clip on the Six O’Clock News showed a PM backed by police saying he’d rather be “dead in a ditch” than delay Brexit. Despite the noise, that signal might be all he needed.

The challenge is to tell one from the other. Some might be tempted to think that the resignation of Johnson’s brother, Jo, is also a mere soap opera twist of import only to the bubble. Wrong. Pollster Deborah Mattinson of BritainThinks reckons, “The brother thing could be a game changer” and will “definitely cut through.” Labour’s line – “If Boris Johnson’s own brother doesn’t trust him, why should you?” – is hugely powerful, says Mattinson, who notes that focus groups still bring up the Miliband brothers, nearly 10 years after they competed against each other. The sheer human drama of siblings at war is compelling. “It’s the stuff of our lives.”

Third question: who unites their tribe? This will be decisive, and it’s why the battle over timing has been so intense. If Johnson can unite the pro-Brexit tribe, he can win – not least because there are more than 400 parliamentary seats that voted leave in 2016. Hence his 35%, core vote strategy. Labour’s only hope is that it can pull off, and improve on, what it achieved in 2017, when it brought most remainers under its banner.

If there is a strategy underpinning Johnson’s recent moves, it’s that desire to ensure hardcore Brexiters have no need to look elsewhere. But it’s fraught with peril. For one thing, it all but writes off the 39% of Conservatives who voted remain, discarding seats in Scotland, London and the south-west. For another, it assumes that onetime Labour voters in the Midlands and northern England who voted leave, and even for Farage, won’t have a visceral resistance to voting Tory. But they might.

Meanwhile, Labour has to hope that the last two years of triangulation on Brexit will somehow be forgotten and forgiven by committed remainers. Recall that four in 10 Labour voters backed the Liberal Democrats in May’s European elections. How can Labour win them back? In an October election the pitch would have been simple: vote Labour to block an imminent no-deal crash-out from the EU. But if and when an extension has been granted, that appeal will lose much of its unifying urgency. Keep an eye too on the so-called Clause V group that will draw up the next manifesto, in which Len McCluskey and the pro-Brexit figures in Jeremy Corbyn’s inner circle loom large. If what emerges is a manifesto promise of a Labour Brexit, two things will happen. Labour spokespeople will tangle themselves in knots, as they explain that Labour will both seek a Brexit deal and campaign not to Brexit. (For a preview, watch Emily Thornberry’s discomfort on Thursday’s Question Time.) And the Lib Dems will have a chance to make a breakthrough, promising a policy as unambiguously against Brexit as Johnson’s is for it.

There are other questions too, of course. Will Johnson be as poor on the campaign trail as he has been this week? Will Corbyn be as good as his backers believe he was in 2017? Or are both now known quantities in the public mind, with little chance of a recurrence of the shifts in opinion that struck two years ago? Will Johnson have the slogan of “Get Brexit over with” all to himself, or could Jo Swinson challenge him by promising to end this national nightmare by revoking article 50? Rarely has there been more uncertainty about an imminent election, from its date to its likely outcome. Only one thing is already known: the stakes are almost unbearably high.

Jonathan Freedland is a Guardian columnist