Brexit is heading toward a cliffhanger finale that could still see Britain crash out of the European Union in nine days without a plan for unwinding 46 years of intricate ties.

The political sands keep shifting and various talks are underway that could still alter Brexit's shape.

Here is a look at the most likely scenarios heading into the 29 March Brexit deadline.

Short deadline delay

Britain on Wednesday formally requested a Brexit deadline extension until 30 June.

The European Commission has advised that a shorter delay until 23 May - before EU member states hold European Parliament elections - or a much longer one until at least the end of 2019 would be better.

EU president Donald Tusk has in any case made the short Brexit deferral "conditional on a positive vote on the withdrawal agreement in the House of Commons".

This vote would most likely happen just a handful of days before the deadline - with the fate of both Brexit and Theresa May's government at stake.

Longer Brexit delay

British Prime Minister Theresa May explicitly ruled out a longer extension both in her letter and appearance in parliament.

A delay of up to two years has been championed by proponents of Europe who want May's strategy to be completely revised - or for Brexit to be reversed in a new national referendum.

"As prime minister, I am not prepared to delay Brexit any further than 30 June," Mrs May said.

Those comments sparked immediate speculation that she was ready to resign if her deal was not voted through next week.

This makes the path to a long postponement more complicated.

It would require parliament to reject Mrs May's deal for a third time.

The UK government must then decide that it cannot go through with the option of simply crashing out of the EU next week.

The other 27 EU leaders then have to unanimously accept the even longer delay.

Theresa May's government would be perilously weakened were she to try to stay on as government leader after seemingly going back on her word.
Second referendum 

Members of parliament last week voted massively against delaying Brexit in order to hold a second referendum.

It was a blow to "People's Vote" campaigners who see it as their best way to keep Britain in the EU.

The pressure for another vote would, however, grow were Brexit delayed beyond 30 June.

The Labour party still views another referendum as an option.

No deal 

The House of Commons last week voted through an amendment saying it cannot accept a scenario under which Britain leaves without a deal.

But this remains the default option - and one whose prospects rose considerably on Wednesday.

Donald Tusk implied that EU leaders were prepared to part with Britain without an agreement were one not voted through in London next week.

Any deadline deferral that comes without parliament's initial backing for Mrs May's pact leaves open the possibility of a no-deal Brexit down the line.

Britain would then revert to trade rules established by the World Trade Organisation (WTO).

Some fervent Brexit supporters see this as a viable economic model.

Businesses worry that the global body is too unwieldy to quickly resolve the litany of trade disputes that will inevitably spring up.

General election 

Theresa May's potential resignation would force her Conservative party to choose a new leader but not necessarily result in a general election.

The House of Commons could force one by voting no-confidence in Mrs May's government. A new election would then be held if no one can form a new cabinet within two weeks.

The Prime Minister also has the option of calling early elections. That motion would also require parliamentary support.