The government was forced into a major compromise on Tuesday when it had to agree to give parliament a greater role in Brexit negotiations to avert a defeat at the hands of rebels from her own party who want to keep close European Union ties after Britain leaves the bloc in March next year.
On Sunday she penned a column in The Sunday Times newspaper saying she had proposed different options for a new customs arrangement with the European Union and that the government would continue to work on them during the negotiations.
MPs voted by 324 votes to 298 to rejecting an amendment passed by the House of Lords in April that would strengthen the hand of the Commons in the event of it rejecting the final Brexit deal.
"The main reason for my taking this decision now is the Brexit process and the government's wish to limit parliament's role in contributing to the final outcome in a vote that takes place today", he said in a statement released on his website.
She said: "I can not countenance Parliament being able to overturn the will of the British people: Parliament gave the decision to the British people, the British people voted to leave the European Union and as Prime Minister I'm determined to deliver that". But Britain's second, unelected, lawmaking chamber attached various amendments, including one of a "meaningful parliamentary vote" on the deal.
How much control lawmakers get of that all-important deal is a question that gathered steam in recent months, with May refusing to grant Parliament a binding vote, saying it would tie her hands in negotiations.
Customs Union: Possible it passes, but odds slightly favour a government win.
Public policy expert Richard Bull of Pinsent Masons, the law firm behind Out-Law.com, said, however, that the MPs would have another opportunity to defeat the government if the promised concessions did not materialise. Known as ping-pong, the bill will move between the commons and the lords until both sides are in agreement on the text - or until the government has made enough concessions for the lords to back down.
"I absolutely trust what the Prime Minister says to us", he told BBC Radio 4's PM programme.
In fact, before the June 12 vote, Britain's justice minister resigned to give him the freedom to criticize the government.
The British government needs to move on from internal debates and make choices about what it wants from Brexit, and must acknowledge that it can not have its cake and eat it, Irish Prime Minister Leo Varadkar said on Wednesday.
On Monday night, she will address her MPs at a private meeting, urging them to "send a message to the country" that the Conservative Party is united on Britain's withdrawal from the EU.
'The Brexit secretary has set out three tests that any new amendment has to meet - not undermining the negotiations, not changing the constitutional role of parliament and government in negotiating worldwide treaties, and respecting the referendum result.