"There will be Conservatives who vote against it come what may, that's why in order for it to pass three things have to happen: she has to get the DUP on board, she has to persuade as many as possible of the 75 (Brexiteer) Conservatives to vote for it, and she will nearly certainly need more Labour MPs", said John Whittingdale, a Conservative lawmaker and member of the pro-Brexit faction.
In another sting for the beleaguered May, U.S. President Donald Trump said he was "surprised at how badly" the Brexit negotiations have been handled.
Ms Siddiq was not at the House of Commons for the voting - she is recovering from the caesarean birth of her son last month - but was able to vote using the proxy system set up in the wake of her appearance in a wheelchair last month.
And fourth, they will vote on a bid by Labour MP Chris Bryant to BLOCK Theresa May from holding a third vote on her Brexit deal.
UK lawmakers gear up for vote on Brexit delay request
Theresa May leaving 10 Downing Street ahead of the vote at Parliament to extend Article 50.
It passed by a 412-202 margin, providing some welcome respite to the prime minister.
May had already lost her voice earlier in the week and did not stand up to speak before the chamber after all the voting had wound down for the day.
DUP leader Arlene Foster said the party was working with the government to try to find a way of leaving the European Union with a deal. "Unless there is a clear majority in the House of Commons for something precise, there is no reason at all for the European Council to agree on a prolongation".
It may well be that the European Union places such conditions on it that a sufficient number of MPs think that a better option would be rather than taking on those conditions, to pass May's deal, when she puts it in front of the House of Commons next Wednesday.
It proposes to hold a series of indicative votes scheduled for March 25, on an alternative approach to the UK's exit from the EU.
She said her preference was for a short delay, meaning the government could try to pass the deal she negotiated with the European Union by the middle of next week, even though it was rejected heavily by lawmakers in January and again on Tuesday.
Noting Thursday's votes in the British parliament to seek a delay in leaving the bloc, a spokesman for the European Commission said: "A request for an extension of Article 50 requires the unanimous agreement of all 27 member states".
"I will appeal to the EU27 (remaining members) to be open to a long extension if the United Kingdom finds it necessary to rethink its Brexit strategy and build consensus around it", he said. Options include a long delay, exiting with May's deal, leaving without a deal or even another referendum.
May's deal has been blocked chiefly by disagreement over the so-called Irish "backstop" - a measure to keep trade flowing and avoid friction at the border between Northern Ireland and the Republic of Ireland.
She added: "They'll know it's a rubbish a deal".
The parliamentary deadlock reflects the deep divisions that remain in Britain three years after the referendum.
The amendment by Hilary Benn, Yvette Cooper and Tory Oliver Letwin would allow 25 MPs from 5 parties to table a motion next Wednesday afternoon - the latest deadline for getting a Brexit deal - to change future Commons business.
"The responsibility for delay is exclusively with my Brexiteer colleagues who did not vote for the deal, and have delayed the process further".
The "People's Vote" campaign said it was premature to push for a referendum now, knowing the motion would be defeated.