LONDON (Reuters) - British Prime Minister Theresa May faces another trial by parliament this week when she must tell lawmakers what progress she has made in talks with the European Union, as patience in her party wears thin and the risk of a disorderly Brexit rises.

Britain's Prime Minister Theresa May attends a summit between Arab league and European Union member states, in the Red Sea resort of Sharm el-Sheikh, Egypt, February 24, 2019. REUTERS/Mohamed Abd El Ghany

May wants to negotiate changes to the exit deal she agreed with the EU last year and has promised to bring it back for approval in parliament by March 12 at the latest.

She will make a statement to parliament on her progress on Feb. 26 and allow lawmakers to debate the issue on Feb. 27.

This week’s debate will not involve a vote on whether to approve or reject a Brexit deal. But it will allow lawmakers to put forward alternative courses of action and there is expected to be an attempt to shift control of the talks out of May’s hands and delay Brexit.

WHAT WILL THEY DEBATE?

Lawmakers will debate a government statement. It is not yet known what this motion will say, but it is not expected to be used to announce a major policy shift.

CAN LAWMAKERS PROPOSE CHANGES?

Yes. They are known as amendments and, if approved by a vote, could change the course of Brexit. Parliament Speaker John Bercow chooses which amendments are selected for debate.

WHAT CAN WE EXPECT?

The likely focus of debate will be on two options on how lawmakers can block a no-deal exit and seek to delay Brexit to allow an extension of negotiations. Britain cannot unilaterally extend negotiations and would need the EU to agree.

With the clock ticking down towards the March 29 exit date, a growing number of lawmakers in May’s Conservative Party are worried about leaving the EU without a deal.

Business minister Greg Clark, work and pensions minister Amber Rudd and justice minister David Gauke have signaled that they will side with rebels and opposition parties to stop Britain leaving without a divorce deal.

WHAT ARE THE OPTIONS?

There are currently two approaches due to be put forward as amendments.

1. The advisory option - Two Conservative lawmakers, Andrew Percy and Simon Hart, are reported to be preparing an amendment which says the government should hold a debate on seeking an extension to the negotiating period if May has been unable to get parliament to approve a deal by March 13. This would not have legal force.

2. The binding option - A cross-party group of lawmakers, led by the Labour Party’s Yvette Cooper, are proposing a plan that would give parliament the legal power to force May to seek an extension.

HOW DOES THE COOPER PLAN WORK?

The first step would be to use an amendment to force the government to allow time in parliament to discuss a piece of legislation known as a bill.

This bill, if approved by parliament, would create a law designed to add safeguards to prevent Britain leaving the EU without a deal. It would not automatically stop or delay Brexit, but could force the government’s next steps.

WHAT SAFEGUARDS?

According to Cooper’s office, the bill will propose:

- If a deal has not been agreed by mid-March, May has to bring a motion to parliament on either a plan to go ahead with a no-deal Brexit on March 29 or a plan to extend the negotiations and for how long.

- Parliament should be able to debate and vote on her plan on the same day.

- If May wants to go ahead with no deal, she needs a majority in parliament.

- If lawmakers reject no deal, May must come forward with a proposal to extend the negotiating period.

- If parliament agrees to May seeking an extension, she has to negotiate that extension with the EU.

WILL IT WORK?

The first stage is winning a vote in parliament on Feb. 27.

The plan is likely to be endorsed by the Labour Party, other small parties in parliament and pro-EU members of May’s party. Several ministers have indicated they will consider supporting the plan even if it means they have to resign or be sacked.

May does not have an outright majority in parliament and is vulnerable to defeat if only a handful of her own party rebel. However, some in the Labour Party would probably vote against the plan.

The publication of the alternative advisory plan by Percy and Hart could also draw support away from Cooper’s amendment and reduce its chances of passing.

There are several more hurdles to clear before it becomes law, including passing contentious legislation that would usually take months in a short space of time - possibly a day.

But, if this succeeds, it will create a significant barrier to May proceeding with a no-deal exit without lawmakers’ consent. Parliament has on previous occasions voted symbolically to say it does not want to leave without a deal.

WHAT DO OPPONENTS SAY?

Pro-Brexit lawmakers, mostly from May’s Conservative Party, argue that the possibility of leaving without a deal would be damaging for the EU and is therefore an important bargaining chip for Britain. They would likely oppose anything which could remove that option from negotiations.

Some argue leaving the bloc without a deal is preferable to leaving with a deal that would keep Britain in a close relationship with the EU, and that any short term economic disruption would be outweighed by long term benefits.