Lawmakers will on Tuesday debate and vote on British Prime Minister Theresa May's response to the overwhelming rejection of her Brexit plan earlier this month.
The vote is not a rerun of the Jan. 15 vote on whether to approve the exit deal she had negotiated with the European Union, which she lost by 432 to 202.
Instead, Tuesday is a chance to discover what sort of changes to her strategy would be required to win the support of parliament, so May can try to renegotiate the deal in Brussels and then ask lawmakers to approve it.
May has said she wants to secure concessions relating to the border with Northern Ireland in order to win the support of pro-Brexit lawmakers in her own party and the small Northern Irish party which props up her government, who voted against her deal.
Some lawmakers want to shift control of the process away from government and give parliament the chance to define Brexit. If successful, this could have a profound effect, giving lawmakers who want to block, delay or renegotiate Brexit a possible legal route to do so.
Other lawmakers have proposed alternatives to May's deal to gauge support for them and persuade the prime minister to change course by seeking closer EU ties or holding a second referendum.
WHAT HAPPENS NEXT?
Lawmakers are officially discussing a bland statement saying they have debated May's next steps. But, using a parliamentary device known as an amendment, some hope to turn it into something that will persuade or force May into taking a different path.
So far 14 amendments have been put forward. The Speaker, John Bercow, will announce at around 1300 GMT on Tuesday which of these have been selected for debate and vote.
Voting on these amendments will take place one by one from 1900 GMT. Each vote takes around 15 minutes and the result is read out in parliament.
Once voting on all amendments has taken place, a vote is held to give final approval to the wording of the statement. This final statement does not automatically dictate government policy.
KEY AMENDMENTS TO WATCH:
AMENDMENT B - Signed by 103 lawmakers
This seeks to shift control of Brexit from May's government to parliament by demanding that on Feb. 5, the rule that government business takes precedence in parliament is overturned.
Providing it has the support of 10 lawmakers from at least four political parties, it makes time for a piece of legislation giving May until Feb. 26 to get a deal approved by parliament.
If not, parliament would be given a vote on asking the EU for a postponement of the Article 50 deadline to prevent Britain leaving without a deal on March 29. It proposes a nine-month extension to Dec. 31.
Put forward by Labour lawmaker Yvette Cooper, this plan has a strong chance of succeeding as the opposition Labour Party has said it is likely to back it and it is supported by several of May's Conservatives.
AMENDMENT N - Signed by eight lawmakers
Supported by Graham Brady, chairman of the influential 1922 Committee of Conservative lawmakers, it calls for the backstop to be replaced with alternative arrangements to avoid a hard border in Ireland and says parliament would support May's Brexit deal if this change were made.
On Monday, May asked her lawmakers to support this amendment. It is potentially useful to the government if passed because it would show the EU there is popular support in parliament for her attempt to renegotiate.
AMENDMENT G - Signed by 74 lawmakers
This has been proposed by Conservative lawmaker Dominic Grieve and has a chance of succeeding as it is supported by lawmakers from several parties.
It demands that, one day a week in February and March, the rule that government business takes precedence in parliament is overturned, giving lawmakers the opportunity to propose their own debates on Brexit. Any proposals approved by parliament on those days would not be binding on the government but would be politically difficult to ignore.
AMENDMENT A - Signed by 52 lawmakers
Proposed by opposition Labour Party leader Jeremy Corbyn, it calls for parliament to consider alternative options to prevent Britain leaving without a deal, including seeking a permanent customs union with the EU and holding a second referendum.
This is unlikely to be approved as pro-EU lawmakers in May's Conservative Party have indicated they will not rebel against their leader by supporting it.
Several Labour lawmakers and the pro-EU Liberal Democrats have proposed changes to this amendment so that it would call only for parliament to vote on holding a second referendum and that remaining in the EU should be an option in that referendum.
OTHER AMENDMENTS THAT COULD BE VOTED ON:
AMENDMENT C - Signed by 11 lawmakers
Proposed by Liberal Democrat leader Vince Cable and his lawmakers, it calls on the government to rule out a no-deal exit and prepare for a second referendum in which the option to remain in the EU would be on the ballot paper.
AMENDMENT D - Signed by 11 lawmakers
Proposed by Liberal Democrat lawmaker Tom Brake, it demands that a committee of no more than 17 lawmakers from across political parties be created and given control of the parliamentary Brexit process.
AMENDMENT F - Signed by 17 lawmakers
This has been put forward by Labour lawmaker Hilary Benn, who chairs parliament's Brexit select committee. It calls on the government to hold indicative votes on the following options:
1) Holding another vote in parliament on May's deal
2) Leaving with no deal on March 29
3) Calling on the government to renegotiate May's deal
4) Holding a second referendum
AMENDMENT H - Signed by 37 lawmakers
Put forward by a group of Labour lawmakers, this calls on the government to request an extension to the Article 50 deadline so that a "Citizen's Assembly" of 250 people can be created to consider the way forward and make recommendations to parliament within 10 weeks of being set up.
AMENDMENT I - Signed by 129 lawmakers
Put forward by Conservative lawmaker Caroline Spelman and supported by lawmakers from most political parties, it seeks to rule out a no-deal Brexit.
AMENDMENT J - Signed by 78 lawmakers
Proposed by lawmakers from Labour, May's Conservative Party and the Liberal Democrats, this calls on the government to request an extension to the Article 50 deadline if a deal has not been approved by Feb. 26.
AMENDMENT L - Signed by 17 lawmakers
Proposed by Conservative lawmaker John Baron, it states that parliament will not approve a Brexit deal which includes a Northern Ireland backstop lasting any longer than six months.
AMENDMENT M - Signed by 18 lawmakers
Also put forward by Baron, it calls for parliament to reject any Brexit deal that does not give Britain a unilateral right to terminate the Northern Ireland backstop.
