LONDON (Reuters) - Britain’s parliament will, over the course of a series of votes on Tuesday evening, decide whether to approve or reject Prime Minister Theresa May’s Brexit deal - a pivotal decision for the world’s fifth largest economy.

FILE PHOTO: Anti-Brexit demonstrators wave EU and Union flags outside the Houses of Parliament in London, Britain, January 30, 2018. REUTERS/Toby Melville

The main vote is on a motion stating that lawmakers in the 650-seat house of Commons approve the Brexit deal. The government needs this approval in order to ratify the deal it has agreed with the European Union.

But, before the big vote, lawmakers will make attempts to change the wording of the motion through a parliamentary device known as an amendment.

These could have the affect of rejecting May’s deal and setting out another path, or adding conditions to the approval.

Any amendments will not be legally binding and so cannot automatically change the government’s course. But, they will be politically powerful and if parliament approves any of them it will be a significant defeat for May.

In some cases defeat on an amendment is so significant that the voting process is halted and the deal is considered to have been rejected. Even minor amendments, could prevent the government from getting the unequivocal approval it needs to ratify the deal.

Six amendments will be selected on Tuesday from all those submitted and can then be put to a vote before the government motion. The selection process is at the discretion of speaker John Bercow. Voting is due to start at 1900 GMT on Tuesday.

Below is a list of amendments that have been submitted so far:

MAJOR AMENDMENTS - Approval of any of these amendment would likely mean instant overall defeat for the government and halt any further votes. May’s deal would have been rejected.

Amendment A

This has been proposed by the leader of the opposition Labour Party, Jeremy Corbyn, and would have three effects:

1) Reject May’s deal

2) Attempt to block Britain leaving without a deal

3) Demand the pursuit of every alternative exit strategy

The pro-EU liberal Democrat party have put forward an amendment to Corbyn’s proposal which specifically refers to a second referendum.

Amendment I

This has been proposed by a group of lawmakers from across the political spectrum, and has received widespread support. It would do three things:

1) Reject May’s deal

2) Attempt to block Britain leaving without a deal

3) Call on the government to set out its next steps to parliament “without delay”.

Amendment K

This has been proposed by Scottish and Welsh lawmakers who say the deal damages their nations. It does two main things:

1) Rejects the existing deal

2) Demands an extension to the Article 50 negotiating period

NORTHERN IRELAND - these amendments relate to the ‘backstop’ arrangement - a fallback policy intended to ensure there is no return to a hard border between British-ruled Northern Ireland and EU-member Ireland.

Amendment M

This has been proposed by lawmakers loyal to Theresa May who, reportedly with the backing of May’s office, want to find a way to get more eurosceptics to vote for the deal. So far it has been dismissed by some of those eurosceptics. [nL8N1YB6X2]

It proposes to give parliament a say on whether to enter the backstop arrangement by ordering the government to report on its progress in March 2020 and then consult on its approach.

Any decision to enter the backstop would need parliamentary approval, and would require the government to have a plan to exit the backstop within a year. It would also require the government to seek similar assurances from the EU about ending the backstop within one year.

Amendment B

This has been proposed by members of May’s Conservative Party. It sets out that Britain will tear up the withdrawal agreement if the EU refuses to agree to a way of ending the special ‘backstop’ arrangements in place for the province.

Amendment D

This has been proposed by a member of May’s Conservative Party. It sets out to make approval of the exit deal conditional on renegotiating to guarantee that a new trade deal is in place. This would negate the need for the unpopular ‘backstop’.

Amendment E

This has been proposed by a member of the opposition Labour Party. It aims to make approval conditional on Britain renegotiating the deal with the EU to win the right to terminate the backstop without needing EU consent.

It also requires the government to seek a different type of future relationship with the EU, modelled on the recently signed trade deal between Canada and the EU.

Amendment F

This has been proposed by a member of May’s Conservative Party. It sets out to make approval conditional on Britain negotiating the right to terminate the backstop without needing EU consent.

OTHERS

Amendment G

This has been proposed by a member of May’s Conservative Party. It would make approval conditional upon an agreement that the only half of the agreed 39 billion pound exit bill would be paid at first, with the second half of payment made only when a free trade agreement with the EU has been ratified.

Amendment H

This has been proposed by a member of May’s Conservative Party. It commits the government to “vigorously contest” any instance where it feels the EU is breaching the requirement to negotiate a future relationship in good faith.

Amendment J

This has been proposed by opposition lawmakers to add additional reassurances that Britain and the EU will ensure open and fair competition and that standards on environmental protection, workers’ rights and safety will not be lowered after Brexit.

Amendment L

This has been proposed by the pro-EU Liberal Democrat party and instructs the government to make all necessary preparations for a referendum on leaving the EU or remaining a member.