What can MPs do to stop a no-deal Brexit? With Boris Johnson insisting that as prime minister he would take the UK out of the EU by the end of October “do or die”, it’s a question that will be asked frequently in the coming months.

If – as expected – Johnson enters No 10 next month, he will have little time to try to negotiate a new Brexit deal with the EU. What’s more, he sees the threat of a no-deal Brexit as key to winning last-minute concessions from Brussels. It follows that a Johnson government will be at pains to keep the option on the table.

The problem? Despite Johnson’s insistence that MPs are coming around to the idea, swathes of parliamentarians are passionately opposed and have promised to do whatever they can to stop it. But what can these MPs actually do to stop a no-deal Brexit?

Speaking on the Today programme this morning, one-time leadership hopeful and now full-time Johnson backer, Dominic Raab, suggested that as prime minister Johnson could simply ignore parliamentary efforts to stop no deal. He said any motion from MPs against a no-deal Brexit would have “zero legal effect” and could be overridden.

This is a view shared by many of Johnson’s parliamentary supporters. They argue that although parliament could vote for numerous motions calling on Johnson to try and extend article 50 or rule out a no deal, he could ignore them. Even a censure motion in which MPs could vote to dock the prime minister’s pay in protest at his decision to keep no deal on the table could have little effect. It’s hardly the case that Johnson is short of funds or likely to be embarrassed.

Johnson supporters argue that unlike Theresa May, he is really prepared to go for no deal. As one cabinet minister said to me: “The problem with no deal last time was not that MPs would not do it, it was that the prime minister would not do it.” There’s a view that May didn’t really fight the Cooper/Letwin amendment forcing the government to seek an article 50 extension as much as she could have.

Q&A What does a no-deal or WTO-rules Brexit mean? Show If the UK leaves the EU without a deal it would by default, become a “third country”, with no overarching post-Brexit plan in place and no transition period. The UK would no longer be paying into the EU budget, nor would it hand over the £39bn divorce payment. The UK would drop out of countless arrangements, pacts and treaties, covering everything from tariffs to the movement of people, foodstuffs, other goods and data, to numerous specific deals on things such as aviation, and policing and security. Without an overall withdrawal agreement each element would need to be agreed. In the immediate aftermath, without a deal the UK would trade with the EU on the default terms of the World Trade Organization (WTO), including tariffs on agricultural goods. The UK government has already indicated that it will set low or no tariffs on goods coming into the country. This would lower the price of imports – making it harder for British manufacturers to compete with foreign goods. If the UK sets the tariffs to zero on goods coming in from the EU, under WTO “most favoured nation” rules it must also offer the same zero tariffs to other countries.

WTO rules only cover goods – they do not apply to financial services, a significant part of the UK’s economy. Trading under WTO rules will also require border checks, which could cause delays at ports, and a severe challenge to the peace process in Ireland without alternative arrangements in place to avoid a hard border.

Some no-deal supporters have claimed that the UK can use article XXIV of the General Agreement on Tariffs and Trade (Gatt) to force the EU to accept a period of up to 10 years where there are no tariffs while a free trade agreement is negotiated. However, the UK cannot invoke article XXIV unilaterally – the EU would have to agree to it. In previous cases where the article has been used, the two sides had a deal in place, and it has never been used to replicate something of the scale and complexity of the EU and the UK’s trading relationship. The director general of the WTO, Roberto Azevêdo, has told Prospect magazine that “in simple factual terms in this scenario, you could expect to see the application of tariffs between the UK and EU where currently there are none”. Until some agreements are in place, a no-deal scenario will place extra overheads on UK businesses – eg the current government advice is that all drivers, including lorries and commercial vehicles, will require extra documentation to be able to drive in Europeif there is no deal. Those arguing for a “managed” no deal envisage that a range of smaller, sector-by-sector, bilateral agreements could be quickly put into place as mutual self-interest between the UK and EU to avoid introducing or to rapidly remove this kind of bureaucracy. Martin Belam

If a motion failed, there is the drastic option of a vote of no confidence in the government. If a majority of MPs voted against the government, it would fall. Unless a new government could be formed, an election would follow. It’s anyone’s guess as to how the Commons would then stop no deal – but if the UK had a general election, there’s an expectation that Brussels would grant a brief extension in a bid to allow the matter to be resolved.

Are there the numbers? Both Amber Rudd and Tobias Ellwood say that they know of enough Tory MPs who would vote against the government if the timing was right. However, both have ruled it out as something they themselves would do on the grounds that it would be a step too far for them to vote down their own government.

The only two Tory MPs to publicly say they would do just this are Ken Clarke and Dominic Grieve. With deselection threats against various pro-EU Tory MPs it could be that more MPs surface – concluding they have little to lose. There would need to be more given that a handful of leave-backing Labour MPs could abstain or prove helpful in the vote as a way to deliver Brexit.

It follows that any Labour plots to hold a confidence vote before the summer holidays begin – as soon as the new prime minister takes office – would likely be premature. Most Tory MPs on the brink say they would only consider it if they believed every avenue had been exhausted and there was no chance of a Brexit deal. Johnson allies believe that the highest chance there is of such a vote succeeding would be in the autumn, when everything is clearer on Brexit.

Given that a confidence vote is seen as a red line, there is one other option to bring the government to a stop to avoid no deal. Tory MPs could refuse to play ball on supply bills and cut off money to the government, thereby bringing it to a halt. Going on strike would send an anti-no deal message without the tagline of bringing down your own government. However, it is still a bold step.

Finally, there is John Bercow, described as an “activist speaker” by Tory MPs. Plenty of pro-EU Conservatives place their hope in Bercow – that he will find a way for MPs to instruct the government to rule out no deal that doesn’t involve bringing the government down in the process. However, Conservative figures suggest they would try and make any such vote a confidence issue in order to call MPs’ bluff. One minister insists: “Very few of these MPs would actually go through with it.”

It follows that a no-deal parliamentary showdown is likely going to come down to a game of bluff – and the Johnson camp are betting on MPs blinking first.

• Katy Balls is the Spectator’s deputy political editor