The stated intent of Boris Johnson’s government to ensure Brexit happens on 31 October, combined with a majority of MPs seemingly set on preventing a no-deal departure, sets the stage for a potential executive versus legislature struggle unparalleled in recent political history. How might such a constitutional crisis pan out?

Could MPs call – and win – a vote of no confidence in Johnson?

They can call one, and Labour has hinted strongly it will do so after the Commons returns in early September. Under the Fixed-term Parliaments Act of 2011, the opposition can table a motion saying: “This house has no confidence in HM government.” Last week’s Brecon and Radnorshire byelection reduced Johnson’s working majority to one, and it is perfectly feasible that a dozen or more Conservative MPs could join opposition parties to vote against him if the only other option were no deal.

No-deal Brexit can still be averted, Labour says Read more

What would happen then?

Unlike under the pre-2011 system, losing a vote of no confidence does not automatically herald a likely general election straight away. Instead, the law introduces a 14-day window in which the incumbent prime minister can try to prove they still command the support of the Commons, or else a new majority government can emerge. If neither happens, there is an election.

Could an alternative government be formed?

Possibly, though there are many political barriers. It seems unlikely under Labour led by Jeremy Corbyn, as there does not seem to be sufficient cross-party support for him to enter No 10. One mooted possibility would be for some form of “national unity” government to take power, perhaps temporarily, to delay Brexit before an election or a new EU referendum, led by a consensual backbencher. However, this would need significant numbers of Labour and Tory MPs to break ranks and join MPs from other parties, all within a very brief window.

Could Johnson force no deal by refusing to resign?

The answer here is somewhere between “yes and no” and “who knows?” As several experts and observers have noted, the law does not make it explicit that a prime minister must resign if they lose a no-confidence vote, meaning Johnson could theoretically sit out the 14-day period before calling an election, by which point 31 October would be almost upon us.

However, as others point out, the political pressure on him to go would be huge, and given an election would be imminent, effectively squatting in Downing Street to get your way would hardly be the best image for the electorate.

Ultimately, prime ministers serve at the request of the monarch, and some have speculated that if a new, unity government was shown to be ready, and to command a Commons majority, the Queen could dismiss Johnson and invite a new prime minister to form a government. It is safe to say Buckingham Palace would very much not enjoy being put in such a position.

Could Johnson secure no deal by ensuring it happens mid-election?

Under the law, the date of the election following a no-confidence vote is a matter for the incumbent prime minister, and given the timetable – parliament returns from recess just over eight weeks before Brexit – Johnson could conceivably decide on a post-31 October polling day.

Some no-deal objectors argue that under the convention of “purdah”, the election period during which civil servants are not supposed to push through any major policy changes, no major Brexit decisions could be taken. However, Johnson could argue that a no-deal departure on 31 October is already the legal default, and so is not a policy change.

Either way, it would be hugely messy and no fun at all for senior civil servants, not least how to communicate no-deal preparations to the public amid purdah, when politically sensitive government messaging is meant to stop.

Could rebel MPs seize control of the Commons order paper?

In theory, yes – and this did happen in March, when MPs hijacked a government motion on the next steps for Brexit, passing an amendment tabled by the Tory grandee Oliver Letwin to hold indicative votes on a departure plan. It is possible that backbenchers could again circumvent the executive and order Johnson to seek a delay to Brexit, make arrangements for a referendum, or even – and this seems unlikely – revoke the whole process.

However, this can only happen if there is meaningful government business on Brexit for MPs to amend, and with no deal seeming the government’s intended course, there might not be any. While there are a series of bills before parliament on post-Brexit arrangements for areas such as fisheries, agriculture and immigration, Downing Street has said it does not believe these need to be passed before 31 October. Another route could be artificially creating parliamentary time for, say, a private member’s bill, but again, this is not an easy process.