Britain's government suffered another setback Wednesday as MPs voted to force it to announce within three sitting days what steps it will take next if its Brexit deal is rejected by parliament next week as appears likely.
The setback for the government came after a day in which senior ministers spoke out about the risks of exiting the European Union without any form of withdrawal agreement.
The government was expecting to have 21 days to come up with a "plan B" for Brexit if, as widely expected, Mrs May's deal is voted down.
"But it is also the intention if that were not to take place, that we would respond quickly and provide certainty on the way forward following that vote".
May postponed an initial vote last month in the face of opposition from all sides of the House of Commons, but has now set it for next Tuesday evening after 1900 GMT, following five days of debate which start on Wednesday.
Earlier on Wednesday, May called on parliament to back her deal, suggesting she was confident of securing further assurances from the European Union to ease their concerns and offering Northern Ireland more control over the "backstop" arrangement to prevent the return of a hard border with European Union member Ireland.
The government has now offered guarantees to devolved politicians in the province over the operation of the backstop, and on the free flow of trade between Northern Ireland and mainland Britain.
DUP MP Gavin Robinson said he did not think the proposals would lead to his party backing the withdrawal agreement.
May is also still seeking assurances on the operation of the backstop from European leaders, which she hopes to deliver before the vote next week.
Following Prime Minister's Questions, the Speaker defended his decision, saying: "It is the long, established practice of this House that the Speaker in this chair makes judgements upon the selection of amendments and those judgements are not questioned by members of the House".
Mr Grieve had tabled the amendment Tuesday night after pro-EU MPs had passed an amendment to the Finance Bill created to prohibit spending on No Deal preparations without authorisation from Parliament - which is dominated by Remainers and largely opposed to No Deal.
May told lawmakers that parliament had a choice: back her or risk Britain leaving the bloc without a deal - a scenario many businesses say would splinter supply chains and hamper investment in the world's fifth largest economy.
A vote, initially slated for mid-December, is now scheduled for January 15 - and the government still looks likely to lose.
Work and Pensions Secretary Amber Rudd told the cabinet that the public would take a "dim view" of government if it settled for a disorderly Brexit and suggested it would make the United Kingdom less safe.
Pro-EU Conservative lawmaker Dominic Grieve, who proposed the measure, said it was meant to speed up decisions, to help avoid a no-deal Brexit and "the calamitous consequences that would follow on from it".
Several Conservative MPs accused Bercow of being biased, and there was speculation of an attempt to remove him from his post.
Labour has said it will seek a confidence vote in the government if it loses next week, and leader Jeremy Corbyn demanded she "do the right thing" and call a general election.