03:38 - Source: CNN
Here's what you need to know about Brexit
Photo Illustration: Getty Images/CNN
Now playing
03:38
Here's what you need to know about Brexit
Britain's Prime Minister Theresa May leaves 10 Downing Street in London on March 25, 2019. - British Prime Minister Theresa May chaired a meeting of her cabinet amid reports of an attempted coup by colleagues over her handling of Brexit. (Photo by Isabel Infantes / AFP)        (Photo credit should read ISABEL INFANTES/AFP/Getty Images)
ISABEL INFANTES/AFP/Getty Images
Britain's Prime Minister Theresa May leaves 10 Downing Street in London on March 25, 2019. - British Prime Minister Theresa May chaired a meeting of her cabinet amid reports of an attempted coup by colleagues over her handling of Brexit. (Photo by Isabel Infantes / AFP) (Photo credit should read ISABEL INFANTES/AFP/Getty Images)
Now playing
01:44
Theresa May to resign when Brexit is done
Pro-EU demonstrators wave an mixed EU and Union flag as they protest against Brexit, outside of the Houses of Parliament in central London on June 11, 2018. - After a rollercoaster week of Brexit rows within her government and with Brussels, British Prime Minister Theresa May will on Tuesday seek to avoid another setback in a long-awaited showdown with parliament. MPs in the House of Commons will vote on a string of amendments to a key piece of Brexit legislation that could force the government's hand in the negotiations with the European Union. (Photo by Daniel LEAL-OLIVAS / AFP)        (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
DANIEL LEAL-OLIVAS/AFP/AFP/Getty Images
Pro-EU demonstrators wave an mixed EU and Union flag as they protest against Brexit, outside of the Houses of Parliament in central London on June 11, 2018. - After a rollercoaster week of Brexit rows within her government and with Brussels, British Prime Minister Theresa May will on Tuesday seek to avoid another setback in a long-awaited showdown with parliament. MPs in the House of Commons will vote on a string of amendments to a key piece of Brexit legislation that could force the government's hand in the negotiations with the European Union. (Photo by Daniel LEAL-OLIVAS / AFP) (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
Now playing
01:07
What's at stake if a Brexit deal falls through
Pedestrians waling through Waterloo Bridge with the skyline of the City of London in the background on October 27, 2016. 
Britain's economy won a double boost on October 27 on news of faster-than-expected growth following its vote for Brexit and a pledge by Nissan to build new car models in the UK. Gross domestic product expanded by 0.5 percent in the third quarter, official data showed.
 / AFP / Daniel Leal-Olivas        (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
DANIEL LEAL-OLIVAS/AFP/Getty Images
Pedestrians waling through Waterloo Bridge with the skyline of the City of London in the background on October 27, 2016. Britain's economy won a double boost on October 27 on news of faster-than-expected growth following its vote for Brexit and a pledge by Nissan to build new car models in the UK. Gross domestic product expanded by 0.5 percent in the third quarter, official data showed. / AFP / Daniel Leal-Olivas (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)
Now playing
02:13
Why Brexit uncertainty means companies plan for the worst
Getty Images
Now playing
03:45
What a fish can tell you about Brexit
Cyclists pass a sign calling for no border to be imposed between Ireland and Northern Ireland outside Newry, Northern Ireland, on November 14, 2018 near the Irish border. - British Prime Minister Theresa May defended her anguished divorce deal with the European Union before rowdy lawmakers on Wednesday before  trying to win the backing of her splintered cabinet with the so-called "Irish backstop" arrangement to guard against the imposition of a hard border between Ireland and Northern Ireland one of the contentious issues, according to reports. (Photo by Paul FAITH / AFP)        (Photo credit should read PAUL FAITH/AFP/Getty Images)
PAUL FAITH/AFP/AFP/Getty Images
Cyclists pass a sign calling for no border to be imposed between Ireland and Northern Ireland outside Newry, Northern Ireland, on November 14, 2018 near the Irish border. - British Prime Minister Theresa May defended her anguished divorce deal with the European Union before rowdy lawmakers on Wednesday before trying to win the backing of her splintered cabinet with the so-called "Irish backstop" arrangement to guard against the imposition of a hard border between Ireland and Northern Ireland one of the contentious issues, according to reports. (Photo by Paul FAITH / AFP) (Photo credit should read PAUL FAITH/AFP/Getty Images)
Now playing
02:06
Brexit: What is the Irish backstop?
CNN
Now playing
01:32
Why there is no easy path in the Brexit deal
EU supporters, calling on the government to give Britons a vote on the final Brexit deal, wave EU flags as they participate in the 'People's Vote' march in central London, Britain March 23, 2019. REUTERS/Henry Nicholls
Henry Nicholls/Reuters
EU supporters, calling on the government to give Britons a vote on the final Brexit deal, wave EU flags as they participate in the 'People's Vote' march in central London, Britain March 23, 2019. REUTERS/Henry Nicholls
Now playing
01:31
Massive crowds march against Brexit in London
Now playing
02:59
May puts the pressure on lawmakers in Brexit address
Parliament TV
Now playing
01:59
Parliament votes to seize control of Brexit process
Parliament TV
Now playing
02:12
Corbyn rips May, demands no confidence vote
parliamentlive.tv
Now playing
01:19
Theresa May's brexit deal suffers historic defeat
EBS
Now playing
02:32
How the EU negotiated its first-ever divorce
CNN
Now playing
01:24
Once pro-leave town feels Brexit uncertainty
Irish border drone footage
CNN
Irish border drone footage
Now playing
01:59
Why the Irish border is impacting Brexit
(CNN) —  

There is an over-used saying about negotiations with the European Union: “Nothing is agreed until everything is agreed.” But in the case of Brexit, that agreement may never come. Britain’s political deadlock over its biggest challenge for decades may never be broken.

In a series of votes in Britain’s House of Commons Tuesday evening, lawmakers will try to take control of Brexit from UK Prime Minister Theresa May’s government, which has failed to get parliamentary approval for her plan for leaving the EU.

Several amendments expected to be put to a vote should, in theory, finally bring some clarity over what kind of Brexit will win the most support.

But that is only in theory.

Even as events unfolded Monday, with momentum building around two key amendments, opposing factions were trying to block them. It is possible that, when the time comes for voting, just after 7 p.m. UK time, nothing will pass.

And with two months to go until Britain is due to leave the EU on March 29, a stalemate makes the prospect of a no deal more likely than ever.

The Northern Ireland backstop

In a bid to break the deadlock, the Prime Minister yesterday put the government’s weight behind an amendment, tabled by a leading Conservative backbencher, Graham Brady, which demands that Brussels reevaluate the Northern Ireland backstop, the insurance policy designed to prevent a hard border with Ireland after Brexit.

Brexiteers despise the open-ended backstop, which means the UK could stay tied to a customs union with the EU forever.

If this amendment is passed, the government would go back to Brussels to ask for a legally binding alternative to the backstop.

The contentious backstop issue was supposedly settled by May and her Cabinet ministers a year ago. So, in backing the Brady amendment, and asking the EU for “alternative arrangements” to be made on the question of Northern Ireland, May has made a significant concession.

In reality, the EU is likely to reject such a bid by Britain – because it wants to protect Ireland’s interests – but it would be significant progress if the Commons backed this measure.

May’s aides have calculated that this amendment would be enough to win support of the broadest possible sweep of MPs from all parties. Yet last night arch-Brexiteers, such as the Conservative backbencher Jacob Rees-Mogg, made clear he and his Eurosceptic colleagues would not support it.

Many of them are becoming increasingly wedded to the idea of a no deal exit: In their eyes, this would mean a clean break with the EU, and freedom to strike trade deals anywhere in the world. In the eyes of British businesses and everyone else in UK politics, it would translate into economic disaster for the country and Ireland, its nearest neighbor.

It is possible, then – but far from certain – that this move will be defeated.

Playing for time

The second key amendment has been tabled by the former Labour minister Yvette Cooper, and would aim to prevent a no deal Brexit by instructing the government to allow more time for talks.

This amendment has been picking up support from both sides, although it is opposed by the hardline Brexiteers.

May, however, is resistant to delaying the date of leaving, as this would take momentum out of her negotiations with Brussels. What’s more, some Labour lawmakers are opposed to the Cooper plan.

But last night, there were signs that, after months of party infighting, Conservatives from opposing sides on Brexit were coming together to try to reach a consensus on an alternative plan – as if heeding the message from the Queen last week that politicians needed to find “common ground.”

This new endeavor proposes extending the transition period, the time during which a new trading arrangement between the UK and EU will be negotiated, for another year, to the end of 2021, making the backstop little more than academic.

Yet this new plan could be too little, too late – particularly because EU leaders have made clear the withdrawal agreement cannot be redrafted.

Yesterday, an unprecedented letter from leading supermarkets and other retailers warned that in the event of a no deal leave, shelves in their stores would be empty by the time of Brexit day on March 29.

This warning will have focused the minds of many lawmakers as they prepare to vote on Britain’s future later today.

But it may not be enough to break the deadlock.

Editor’s note: This piece was updated to clarify the terms of Graham Brady amendment.