Quitting the EU after 46 years on 29 March remains the legal default unless EU leaders unanimously grant Britain an extension, with the issue likely to dominate a 21-22 March EU summit in Brussels.
Next week, May will be hoping that the threat of a longer delay to Brexit will convince Conservative rebels to finally back her revised withdrawal agreement.
The vote against a no-deal Brexit was non-binding, but investors believe Britain will now avert a disorderly Brexit that would severely damage its economy.
"Psychologically, it is important that we change this, because the European Research Group thinks this is a trick", Seif said.
Pro-Brexit lawmakers in May's Conservative Party have rejected her withdrawal deal-which lays out the terms of Britain's departure and the outline of the country's future relations with the European Union -because they think it keeps Britain too closely bound to the bloc's rules and regulations.
The British government is holding talks with Northern Ireland's Democratic Unionist Party, which has strongly opposed the Brexit divorce deal. In northern Ireland, decades of sectarian violence between protestants, who wanted to remain with the United Kingdom and Catholics, who wanted join Ireland, came to an end after the 1998 Good Friday agreement.
Her Cabinet (members) are disloyal and she has lost two major votes on her deal.
MPs voted to extend Article 50 until 30 June by a majority of 412 to 202.
If not, she'll seek a longer extension, which, she warns, may kill Brexit.
With less than two weeks before Britain is due to leave the EU, Mrs May seems to be clinging on to her waning authority by a thread after a series of humiliating defeats.
Unless May can get a Brexit deal approved by the British parliament, then she will have to decide whether to delay or cancel Brexit or thrust the world's fifth largest economy into chaos by leaving without a deal.
A new vote on May's deal is likely next week, when those lawmakers must decide whether to back a deal they feel does not offer a clean break from the European Union, or reject it and accept that Brexit could be watered down or even thwarted by a long delay.
The Labour MPs Yvette Cooper and Hilary Benn and the Conservatives Sir Oliver Letwin and Nick Boles wanted to seize control of the parliamentary agenda to force a relaxation of the prime minister's red lines. Barley, who is half British, told RBB radio on Friday that "giving more time alone will produce no solution".