Seeking to break Britain's Brexit deadlock, Prime Minister Theresa May said on Tuesday she plans to ask the European Union to change its divorce deal with the UK by altering an Irish border guarantee that is opposed by many British lawmakers.EU leaders have ruled out any renegotiation on the Brexit deal, but May urged Parliament to give her a mandate by backing a call for the border measure to be replaced by unspecified "alternative arrangements"."Today we have the chance to show the European Union what it will take to get a deal through this House of Commons; what it will take to move beyond the confusion and division and uncertainty that hangs over us," May told lawmakers.The House of Commons was voting later on Tuesday on competing Brexit proposals that have been submitted by both pro-Brexit and pro-EU legislators since Parliament rejected May's divorce deal two weeks ago, leaving Britain lurching toward a cliff-edge "no-deal" departure from the bloc on March 29.Speaker of the House of Commons John Bercow selected seven proposals for debate and vote, including the border change supported by May and several measures that seek to rule out a "no-deal" Brexit.But amid political gridlock in London and with Brexit day just two months away, the EU shows few, if any, signs of renegotiating the divorce deal it struck with May late last year.May, who planned to call EU leaders on Tuesday, insisted that her agreement could still win Parliament's backing if it was tweaked to alleviate concerns about the Irish border measure, known as the backstop. The backstop would keep the UK in a customs union with the EU in order to remove the need for checks along the border between the UK's Northern Ireland and EU member Ireland after Britain leaves the bloc.The border is crucial to the divorce deal because it will be the only land frontier between the UK and the EU after Brexit, and because the free flow of people and goods underpins both the local economy and Northern Ireland's peace process.Opposition to the backstop by pro-Brexit lawmakers — who fear it will trap Britain in regulatory lockstep with the EU — helped sink May's deal on January 15, when Parliament rejected it in a 432 to 202 vote.May backed a proposal from a Conservative lawmaker calling for the Irish backstop to be replaced by "alternative arrangements", and called on all legislators from her Conservative Party to support it.May said it was a chance to "tell Brussels that the current nature of the backstop is the key reason Parliament cannot support this deal".May's approach drew praise from Brexit-backing lawmakers but prompted scorn from their pro-EU colleagues.Green Party legislator Caroline Lucas accused May of chasing "heated-up fantasies that have already been rejected by the EU".Lawmakers dividedIt's far from certain that the amendment will win support from a majority in the House of Commons when it comes to a vote later on Tuesday. And the EU insists the legally binding withdrawal agreement cannot be renegotiated.Ireland's European Affairs Minister, Helen McEntee, said British politicians needed to show "a bit of realism"."There can be no change to the backstop. It was negotiated over 18 months with the UK and by the UK," she said.Although Parliament is overwhelmingly opposed to May's Brexit deal, lawmakers are divided over what to do instead — whether to brace for a "no-deal" Brexit or to try and rule that out.Much of the business world says a no-deal Brexit would cause economic chaos by eliminating existing EU trade agreements and imposing tariffs, customs checks and other barriers between the UK. and the EU, its main export market.Opposition Labour party leader Jeremy Corbyn said his lawmakers would support amendments intended to "block a disastrous no-deal."He said May had done nothing but "double down on her own defeated deal," rather than seeking a compromise with lawmakers from all political viewpoints.Tuesday's votes will not mark the end of Britain's turmoil over Brexit. May said if she has not struck a new Brexit deal by February 13, Parliament would get to vote, again, on what should happen next.EU leaders have repeatedly urged Britain to clarify what kind of Brexit it wants and are watching to see which proposals — if any — get the backing of the UK Parliament."This is not a Brussels day, this is a London day," said European Commission spokesperson Margaritis Schinas. "(They) have the vote tonight and then we will take it from there.