London (AFP) -

With Prime Minister Theresa May on Tuesday asking MPs to give her more time for talks with Brussels to renegotiate her Brexit deal, it remains unclear how Britain will leave the European Union.

EU officials have ruled out re-opening the withdrawal agreement -- the legally binding part of the Brexit deal -- but British officials are hopeful that some compromise will be found.

Three ultimate scenarios remain -- leaving the European Union with a version of the existing deal, crashing out with no deal, or no Brexit at all.

Here are five potential next steps:

- Try to alter the deal -

MPs last month roundly rejected the deal negotiated by May in the biggest ever parliamentary defeat for a government.

The key sticking point is the agreement's "backstop" solution to keep the Irish border open, which has the potential to leave Britain indefinitely tied to some form of EU customs union.

Brexit hardliners from the Conservative Party's European Research Group have urged May to try and secure legally-binding changes to the backstop.

Northern Ireland's Democratic Unionist Party, which May relies on for a majority in parliament, has also said it will not vote for a deal with the backstop as it stands.

The main opposition Labour Party has signalled that it could support the deal if the government commits to a permanent customs union with the EU but May has ruled this out.

EU leaders have said they are willing to talk further, including on plans for the future trading relationship, but have repeatedly said they will not reopen the withdrawal agreement itself.

- No deal -

Britain is legally on track to leave the EU with or without a deal on March 29, unless it delays or stops the process.

Leaving with no deal in place threatens to trigger a recession in Britain and markedly slow the EU's economic growth, as well as causing significant legal disruption.

One of the world's biggest economies could lose preferential access to its largest export market overnight, affecting every sector, leading to rising costs and disruption at British ports.

- Delay -

Speculation has been growing that the government will instead seek to postpone the Brexit process.

Government ministers have spoken of a technical extension but some reports have suggested the delay could be two or three months or even longer.

Political analysts argue lawmakers could still back such a postponement further down the line -- although all the other 27 EU countries would have to agree.

A potential complication is that elections to the European Parliament are due in late May and the new chamber is set to sit on July 2. Some of Britain's 73 seats have already been reallocated.

Brussels also may not be so keen if the delay would simply translate into more months of political gridlock.

- Second referendum -

Dozens of MPs are seeking a new referendum to reverse the 2016 result, when the Leave campaign won by 52 percent to 48 percent.

But supporters admit they do not currently have the numbers in parliament to make it happen.

No law prevents Britain from doing it all over again, but many question whether a re-run would be democratic -- or resolve anything.

May has warned that another vote "would do irreparable damage to the integrity of our politics".

It also threatens to be just as divisive as the last one, with opinion polls showing the country is still split over the issue.

- General election -

It is a long shot but some reports have suggested the prime minister could call a snap vote in a bid to break the impasse.

The most recent polls indicate the Conservatives could win a slender majority, meaning that the political rough-and-tumble seen since the 2016 referendum would likely continue. 

The only other way for an election to be called would be for parliament to vote no confidence in the government, but at this stage it looks unlikely as Labour already tried and failed to pass such a vote last month.

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