British Prime Minister Theresa May holds a press conference within the session of the European Council over Brexit, on November 25, 2018 in Brussels.

Time is running out for U.K. Prime Minister Theresa May to get a deal done before Britain is officially supposed to leave the EU on March 29.

The lower house of the U.K. Parliament, the House of Commons, is scheduled to carry out a series of votes this week.

The first will be a second attempt at passing May's Brexit deal. If this fails again it will be followed by a vote on ruling out a no-deal scenario, and then a vote on whether the U.K. should seek to extend Britain's leaving date beyond the end of March.

May has already agreed a draft withdrawal deal with Brussels that sets the terms by which the U.K. leaves the bloc. Among other things this includes what money is owed, how citizens will be treated, as well as what happens at the land border between EU-member the Republic of Ireland and U.K.-ruled Northern Ireland.

However, the U.K. Parliament has to approve the terms and in the first "meaningful vote," back in January, lawmakers overwhelmingly rejected the 585-page treaty. Most of the dissatisfaction centered around a safety net arrangement known as the "Irish backstop."

The backstop is designed to ensure that should Britain and the EU fail to resolve their future trading arrangements, there can be no possibility of a physical border being erected within the island of Ireland.

It is hated by Euroskeptic lawmakers who fear it will trap the U.K. into a never-ending customs union with Europe. This is seen as the main reason May's deal failed at the first vote and efforts to overcome this are underway before a second meaningful vote is to be held.

Britain's top lawyer, Attorney General Geoffrey Cox, had visited Brussels in recent days to try to negotiate terms that will satisfy doubtful lawmakers but had little success. The EU has tried to reassure the U.K. that the backstop is a last-resort and could apply only to Northern Ireland, rather than the whole U.K. but that is also an unpalatable prospect for many British politicians.