I’m sorry to interrupt your summer but this country is being ruled by alt-right maniacs who want to destroy parliamentary democracy. They’ve announced it in plain sight: if parliament votes to stop a no-deal Brexit, Boris Johnson’s government will try to ignore it.

If forced to call an election they will do so in a way that triggers a catastrophic no-deal crisis, plunging hundreds of thousands of small businesses into the red and collapsing the pound. The government headed by a man who once said “fuck business” really intends to “fuck” not only business, but democracy and civil society too.

The question, then, is what are we going to do about it? Drawing on discussions with senior progressive politicians also struggling with this dilemma, I will suggest – in a clear sequence – some solutions, and who can make them happen. There are choices but no unicorn options, as all outcomes are limited in both scope and time.

First, when parliament returns on 3 September, the pro-remain Tory rebels need to join opposition parties in a move to take control of the order paper (through Standing Order 14). They need to prepare short, sharp primary legislation that blocks no deal. I understand talks about this are under way – but the intentention and the timing needs to be communicated to the electorate and the party memberships openly.

There is nothing to stop Labour tabling a vote of no confidence on the first day back, and they should do that. But it will very likely fail.

There is no guarantee the ex-Labour independents will vote for it, nor MPs like John Mann and Kate Hoey. The Tory rebels will not do so until they have exhausted attempts to control parliament. Despite that, the vote should be tabled simultaneously with the takeover of the order paper: watching Chukka Umunna and Jo Swinson squirm and prevaricate, and even Philip Hammond be forced to support Johnson, should be worth a good five percentage points for Labour.

If the Standing Order 14 gambit succeeds, and the Commons enacts legislation to prevent no deal, it is highly likely Boris Johnson will attempt to defy that. If so, a large number of pro-Remain and liberal Conservatives would have just cause to vote him out of office. That is what makes a second vote of no confidence likely, and is the best guarantee of collapsing the current government.

Here is where the choices open up for Labour and the other progressive parties. The opposition would have 14 days to form a government. As leader of the opposition, Jeremy Corbyn should be given first go at forming a minority administration with the confidence and supply of others. All noises from the Lib Dems and Tory rebels say they won’t do this, but it should at least be tried.

That government would set itself a very limited remit: to pass a one-year budget to end austerity (for which there is now cross party consensus), to request a further extension from the EU, and to organise a second referendum within six months.

Since the Lib Dems and Tory rebels could pull the plug on Corbyn at any time, and moreover could demand oversight via the committee system if not Cabinet, their complaints that they “don’t trust” Corbyn, or fear his national security strategy, are fatuous. Nevertheless, they may succeed in blocking a minority Labour government.

In that case, the fall-back option should be a temporary coalition government with the same aims as above: a budget, an extension and a referendum. Don’t insult people by calling it a “government of national unity” – there is severe disunity in the country, and it should assume no mandate for anything but a budget, a delay and a referendum.

Whether Corbyn should lead that coalition is irrelevant: I doubt he would want to lead a cross-party cabinet anyway. A senior Labour backbencher with no leadership ambitions might make the best prime minister. Or, in extremis, a senior progressive figure in the Lords.

For Labour members, the important thing to grasp is this: if Labour ends up leading as a coalition or as a minority government, without a general election it will have no mandate to “do its own Brexit deal”. This fantasy-island option, still being peddled by Unite in the Labour conference process, is an irrelevant delusion. The only deal on the table is the one May agreed with Barnier, and any changes to it would be for the EU to propose. A minority Labour government would have no mandate whatsoever to do a new deal, and should not try to.

However, if we do end up with a snap general election, it would be fatal for Labour to go into it trying to fudge on its desired Brexit outcome. Corbyn would be walloped around studios by TV and radio presenters, and walloped in any head-to-head leadership debates.

Labour’s position has moved: it now stands for a second referendum on any deal, and is prepared to vote Remain. Corbyn must, by early September, clarify that in any general election Labour would propose in its manifesto to Remain in the EU, but hand the ultimate decision quickly to the people, in a referendum to be called within six months of taking office.

We can’t wait for Labour conference to decide this: if Brighton turns into a bloodbath between the Lexiteers, the unions, the Blairites and the internationalist left you can kiss the election campaign goodbye.

It is certain that any snap election would become a proxy referendum on our relationship with Europe. Labour’s army of campaigners simply will not turn out enthusiastically for another fudge; they were deeply scarred by the experience of the European election campaign, where progressive former Labour voters slammed the doors in their faces.

So in a snap election, Labour should present a focused left-wing programme for government with a remain and transform strategy for the EU, and the offer of a referendum by March at the latest.

On that basis Labour should attempt a non-aggression pact with the Greens, Lib Dems, Plaid Cymru and the SNP. It won’t be easy, but the purpose of such tactics is to show voters who’s serious about preventing no deal, and defending democracy, and who is not. Tom Watson’s talks with Jo Swinson, together with research circulating inside the People’s Vote campaign, suggest the practical outcome of an electoral pact might be as follows.

First, the parties declare they will focus all their fire on the Tories, Nigel Farage and their racist American backers, not on each other. Second the party machines issue clear instructions to stand paper candidates in an agreed list of seats. Third, where possible, they pool campaign resources – with Labour and the left-wing parts of the Greens this should be entirely possible. As I have argued before, Labour should offer Caroline Lucas a place in the shadow cabinet, and a major ministry if we form a government.

To be clear: in all Scottish seats held by the Tories, the realistic challenger is the SNP. Out of the top 50 marginal seats in England held by the Tories, only five are realistically winnable by the Lib Dems, while 43 would clearly go to Labour under this arrangement. In Wales Labour is the clear challenger in five Tory seats, while only in Dwyfor Merionedd, where Liz Savile Roberts is MP, would it make sense for Labour to stand aside.

The wild card is the Brexit Party. If Farage decides to stand candidates only against Labour, giving Johnson a free ride everywhere else, we will be lucky if the Tory majority is less than 50. If, however, he remains determined to split the xenophobic vote, that makes it easier for Labour to win in the English Midlands – but this is no excuse for failing to plan for the worst-case now.

The costs and chances of losing such a snap election are much higher than under Theresa May – and the tactics have to change accordingly. So come what may, I will personally try to make this happen from below. But it would be better if the agreement were reached honestly and openly by party leaders.

If an electoral pact produces Labour plus SNP/Green government, even better, because it will have the mandate for major constitutional change.

No progressive voter in Britain can be in any doubt about what is at stake: we’re either going to become a colony of the sick, violent society Trump is creating in the USA, or a leading (and militarily decisive) force in Europe, either within the EU itself or in the single market or closely aligned to it. Paradoxically, the threat of Trump and the magnitude of what a Trump-Johnson trade deal would do to UK civil society make the differences between full membership and the EEA secondary.

If you don’t agree with this course of action, please tell me how you intend to stop no deal, or to achieve a Labour government, or – and this is the bigger thing – save British democracy from a Whitehall coup. You may tell me “I’ve been a Labour tribalist all my life, I can’t face this” – but I am frankly sick of hearing this from politicians and union leaders.

What they mean is that they would rather have a commemorative plate for the great, failed experiment of a left-led Labour Party than to defeat the Tories and the far right through struggle.

If you do agree, tell your MP and start talking locally, across the party boundaries with activists from other progressive parties. If your MP comes out with garbage like “I’m a tribalist and I’m sick of referendums”, just deselect them in a trigger ballot.

Come the end of October, we’re going to be facing an open power-grab by Johnson and his deranged clique. They need to be on the receiving end of a mass, active defence of British democracy.