Theresa May faces a series of crunch Commons votes on Tuesday which could dramatically alter the entire Brexit process.

But will this be a “high noon” moment or just another staging post in the chaotic impasse gripping parliament?

The frustrating, but honest, answer is that it completely depends on what happens.

By the end of Tuesday, Brexit could be on the verge of being delayed, Theresa May could have a mandate to ask the EU for fresh concessions on her deal, or we could be one step closer to no deal. 

So how will it play out?

Factions of MPs have put forward a range of rival plans they hope will provide a solution to the Brexit mess, in the form of amendments.

Commons Speaker John Bercow will be poring over these amendments and deciding which of them he will select for MPs to vote on.

He is expected to choose around six, and will take into account how many MPs have so far indicated their support for each plan in making his decisions.

Those selected will then go forward to a vote in the House of Commons. 

If MPs approve certain amendments they could have a big impact on Brexit.

So which plans have a chance, and what effect will they have?

Labour MP Yvette Cooper’s amendment to delay Brexit and avoid a no-deal scenario is the most dramatic.

Put simply, it would upend longstanding parliamentary procedures to allow MPs to compel the prime minister to extend the Article 50 Brexit process beyond the planned EU leaving date of March 29, if May has not passed a deal by February 26.

The Cooper amendment would appear to have enough support from Tory Remainer rebels to pass, as long as Bercow selects it and Labour throws its full weight behind the plan, which seems likely given Jeremy Corbyn’s desire to rule out a no-deal Brexit.

Dominic Grieve’s amendment would again rip up Commons procedures to give MPs the chance to debate and vote on various different Brexit ‘plan Bs’ on six separate days in the run up to the March 29 exit day. 

The Tory rebel hopes this will allow MPs the time and space to work out whether any plan – be it a second referendum or a Norway-plus trade deal with the EU, or something else – can command a parliamentary majority.

Like Cooper’s amendment, if it is selected by Bercow and Labour back it there could be enough Tory Remainer rebels to ensure it passes.

Senior Tory MPs Andrew Murrison and Sir Graham Brady have put forward two separate plans which would specify an end date for the controversial Irish backstop, or seek to scrap it from May’s deal entirely.

Neither plan would have any practical effect as the deal is subject to negotiation with the EU.

But May could order government MPs to back one in the hope that if it passes, it will strengthen her negotiating hand in Brussels as she would be able to demonstrate exactly what the EU must concede on to allow the deal to pass.

There are two key obstacles to these amendments, though.

Firstly, Bercow may decide not to select either if he suspects they have the whiff of government support.

And even if he does, Tory hard Brexiteers in the European Research Group will have to back them, as opposition parties are opposed.

A cross-party amendment put forward by Tory Dame Caroline Spelman and Labour’s Jack Dromey would simply give MPs a chance to reject a no-deal Brexit.

It looks likely to pass, if selected, but would have no legal effect and would not actually stop no-deal as the March 29 exit date is written into law.

It would, however, put May under huge political pressure to rule out no-deal, potentially forcing her to delay Brexit and rewrite her strategy.

What happens if none of the amendments pass?

Both the prime minister and parliament will be stuck between a rock and a hard place.

MPs will have failed to take control and May will have little hope of persuading the EU to make fresh concessions on the deal.

Britain would then be on course for a no-deal Brexit unless the PM changes tack, the Commons finds some other means to stop the clock or change the government’s plan, the EU panics and makes concessions on the backstop, or MPs change their minds and back May’s deal.