LONDON (Reuters) - British Prime Minister Theresa May has sought to break the parliamentary deadlock over Brexit by proposing to seek further concessions from the European Union on a plan to prevent customs checks on the Irish border.

An anti-Brexit protester walks outside the Houses of Parliament in London, Britain January 17, 2019. REUTERS/Clodagh Kilcoyne

On Jan. 29, parliament will debate May’s proposed next steps as well as alternative plans put forward by lawmakers, including some that seek to delay Britain’s March 29 exit by requesting an extension to the two-year Article 50 negotiation period.

Some also seek 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.

Below is what is due to happen next:

JAN. 21-29: LAWMAKERS PROPOSE ALTERNATIVES

Lawmakers have begun proposing alternatives to May’s next steps through a parliamentary device known as an amendment. Amendments will be selected on Jan. 29 by speaker John Bercow and can then be put to a vote.

Below are the amendments that have been put forward so far:

AMENDMENT A

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 Conservative lawmakers have indicated that they will not support it.

AMENDMENT B

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 C

This has been put forward by Labour lawmaker Hilary Benn, who chairs parliament’s Brexit select committee.

It calls on the government to hold a series of 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 D

Proposed by lawmakers from Labour, May’s Conservatives and the pro-EU Liberal Democrats, this calls on the government to request an extension to the Article 50 deadline.

AMENDMENT E

Put forward by Labour lawmaker Yvette Cooper, it is supported by several of May’s Conservative lawmakers and therefore has a chance of succeeding.

It 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 then makes time for a piece of legislation Cooper has proposed, which gives May until Feb. 26 to get a deal approved by parliament.

If the government fails to get a deal through by that date, 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.

AMENDMENT F

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.

JAN. 29: PARLIAMENT DEBATES AND VOTES ON NEXT STEPS

Parliament will hold a day of debate on May’s proposed next steps and lawmakers’ amendments. They will not be asked to vote to approve a revised Brexit deal at this stage.

A vote in favour of changing the parliamentary rules would change the long-held principle of the British parliament that the government has control of what has the chance to become law.

Votes on alternative types of deal proposed by lawmakers should give an indication of whether there is any way forward supported by a majority in parliament.

If an option were approved by a majority of lawmakers, May could go back to the EU and seek changes to her Brexit deal. Parliament would ultimately still need to vote on any revised deal.