THERESA May has set out plans to short circuit parliamentary rules in order to get a Brexit deal ratified in time for the UK to leave the EU on March 29.

The Prime Minister told MPs that she would enable the House of Commons to lift a requirement for a 21-day delay before any vote to approve an international treaty.

This will allow May to hold the vote on her deal any time up until March 29, forcing MPs to choose between her deal and a no-deal Brexit.

The announcement came as May urged MPs to "hold their nerve" and support her efforts to secure a withdrawal deal which will deliver Brexit on time.

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In a statement updating the Commons on progress in Brexit talks, May acknowledged she would need "some time" to seek legally binding changes from the EU to the controversial backstop for the Irish border.

She confirmed that she will table an amendable motion for debate on Thursday, seeking the House's continued support for her to demand "alternative arrangements" to keep the border open after Brexit.

And she pledged to return on February 26 with a further statement triggering another debate and votes the following day if she has not secured a deal by that date.

If a deal is agreed, MPs will have a second "meaningful vote", like the one in January which saw Mrs May's original plan rejected by a record-breaking 230 votes.

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The February 27 votes are expected to come shortly after May's planned meeting with European Commission President Jean-Claude Juncker, at which changes or additions to the Withdrawal Agreement could be agreed.

The National:

With 45 days to go, former attorney general Dominic Grieve warned that time was running perilously short for ratification of any deal under the terms of the Constitutional Reform and Governance Act.

The Act, passed by the coalition government in 2010, requires 21 sitting days before the ratification of any international treaty.

But May responded: "In most circumstances, that period may be important in order for this House to have an opportunity to study that agreement.

"But of course, in this instance MPs will already have debated and approved the agreement as part of the meaningful vote.

"So while we will follow normal procedure if we can, where there is insufficient time remaining following a successful meaningful vote, we will make provision in the Withdrawal Agreement Bill - with Parliament's consent – to ensure that we are able to ratify on time to guarantee our exit in an orderly way."

A spokesman later explained that the process would be accelerated by a clause in the Withdrawal Agreement Bill itself, which would disapply the terms of the 2010 Act in this case.

May sidestepped demands from several MPs to spell out whether she would ask the EU for an extension to the two-year Brexit negotiation process or allow the UK to crash out without a deal if she hit the March 29 deadline with no agreement.