FILE PHOTO: Britain's opposition Labour party leader Jeremy Corbyn appears on the BBC's Andrew Marr Show, in London, Britain January 13, 2019.
LONDON, Jan 23 (Reuters) - An attempt by British lawmakers to prevent a no-deal Brexit was gaining momentum on Wednesday after the opposition Labour Party said it was highly likely to throw its parliamentary weight behind the bid.
The United Kingdom, in the deepest political crisis since World War Two, is due according to law to leave the European Union at 2300 GMT on March 29 yet it has no approved deal on how the divorce will take place.
Prime Minister Theresa May is battling to break the deadlock after last week's crushing defeat of her two-year attempt to forge an orderly divorce with close post-Brexit ties with the EU has raised the prospect of an exit without a deal.
In a step that could overturn centuries of constitutional convention, some British lawmakers are trying to grab control of Brexit from the government in an attempt to prevent what they say would be an economically disastrous no-deal Brexit.
The opposition Labour Party is "highly likely" to back one such attempt, an amendment proposed by Labour lawmaker Yvette Cooper that could result in May being given until Feb. 26 to get a deal approved by parliament or face a parliamentary vote on delaying Brexit.
"Yvette Cooper has put an amendment down which I think is sensible," John McDonnell, the second most powerful man in the Labour Party, told the BBC.
When asked whether Labour would back the amendment, he said: "Highly likely."
Sterling rose to a two-month high of $1.3005.
As the United Kingdom's tortuous two-and-a-half year crisis over EU membership approaches its finale, the options for the world's fifth largest economy include a no-deal Brexit, a last-minute deal, a snap election or a delay to Brexit.
May has warned that thwarting Brexit will threaten social cohesion because it will undermine the belief in British democracy while police cautioned the "febrile" atmosphere could be exploited by far-right extremists.
Parliament will vote on Jan. 29 on different options put forward by lawmakers, potentially opening up a way out of the stalemate.
If the Cooper amendment is passed, it would effectively give parliament the power to set May a deadline of Feb. 26 to get a deal approved by parliament.
If she fails, 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.
Another alternative is that May gets enough concessions from the EU to win over rebels in her Conservative Party as well as the Northern Irish party which props up her minority government.
EU Economic Affairs Commissioner Pierre Moscovici said in Davos on Wednesday the risk of a no-deal Brexit had increased and it was up to the British to tell the EU how they proposed to break the impasse.
"The gravity of the situation lies in the fact that London is silent," an EU diplomat said.