Efforts to persuade MPs to back Theresa May’s Brexit deal will continue on Thursday, a day after she promised to quit as PM if it was approved.
Her pledge brought some on-side, such as ex-Foreign Secretary Boris Johnson.
But challenges remain for the PM after Northern Ireland’s DUP, who she relies on for support, said it would not back the deal because of the Irish backstop.
Meanwhile, none of eight alternative Brexit proposals brought by MPs secured backing in a series of Commons votes.
The options – which included a customs union with the EU and a referendum on any Brexit deal – were supposed to help find a consensus over how best to leave the EU.
But the failure of any of them to garner support from a majority of MPs led Brexit Secretary Stephen Barclay to say it strengthened ministers’ view their deal was “the best option”.
Ahead of the debate heralding the “indicative votes”, Mrs May told a meeting of Conservative backbenchers she would leave office earlier than planned if it guaranteed Parliament’s backing for her withdrawal agreement with the EU.
Mrs May told her MPs: “I have heard very clearly the mood of the parliamentary party. I know there is a desire for a new approach – and new leadership – in the second phase of the Brexit negotiations – and I won’t stand in the way of that.”
She told MPs she would resign as party leader after 22 May – the new Brexit date – but stay on as PM until a new leader is elected. However, Downing Street said it would be a “different ball game” if the deal was not passed.
Her announcement that she would not lead the talks with Brussels over the future relationship between the UK an EU prompted a number of Tory opponents of her deal to signal their backing.
Prominent Leave supporters such as Mr Johnson and former Tory leader Iain Duncan Smith said they now viewed the deal as the least-worst option.
But Mrs May needs to win over 75 rebels to overturn the 149-vote rejection of her deal on 13 March.
Jacob Rees-Mogg, who chairs the Brexiteer European Research Group (ERG), said he would only support the deal if the 10 MPs of the DUP did so.
“I won’t abandon the DUP because I think they are the champions of the Union of the United Kingdom,” he told the BBC.
The DUP’s main objection is to the backstop, the “insurance policy” designed to avoid the return of border checkpoints between Northern Ireland and the Republic of Ireland in the event a future trade deal is not agreed.
It argues that the measure would result in Northern Ireland having to abide by different trade rules to the rest of the UK, which leader Arlene Foster says would “damage the Union”.
“The backstop in that Withdrawal Agreement makes it impossible for us to sign up to the agreement,” she told the BBC.
Meanwhile, ERG vice-chairman Steve Baker suggested he may resign the Conservative whip rather than vote for the deal.
The prime minister offered to pay the ultimate price, and leave office – the grandest of gestures any leader ever really has.
For a moment it seemed it might work and line up the support she so desperately needs.
But within a couple of hours her allies in Northern Ireland were refusing to unblock the progress of Theresa May’s main mission.
That might not be terminal – one cabinet minister told me the PM may yet have another go at pushing her deal through Parliament against the odds on Friday.
But if Plan A fails, Parliament is not ready with a clear Plan B that could yet succeed.
For our politics, for businesses trying to make decisions, for all of us, divisions and tensions between and inside our government – and our Parliament – are too profound to bring this limbo to an end.
Despite this, Mrs May is thought to be considering a third attempt to get MPs to back the deal, potentially on Friday.
However, there are signs her offer to resign has hardened Labour opposition.
Shadow cabinet sources told the BBC potential Labour rebels would not want to make it easier for the PM to make way for a Brexiteer successor.
If Mrs May’s deal is not approved this week, MPs are likely to resume discussions about some of the options rejected through the indicative voting process.
Commons Speaker John Bercow said on Wednesday the process agreed by the House allowed for a second stage of debate on Monday and there was no reason this should not continue.
While it was up to MPs, he said there was an understanding Wednesday’s objective was to “shortlist” a number of options before moving on to consider the “most popular”.
Mr Barclay, however, appealed to MPs to back the PM’s deal “in the national interest”.
“The House has considered a wide variety of options as a way forward,” he said.
“And it demonstrates there are no easy options here. There is no simple way forward. The deal the government has negotiated is a compromise…That is the nature of complex negotiations.”