Theresa May has said she is working on getting further assurances from the European Union so she can win the Commons vote on her Brexit deal.
The PM said that after delaying the vote last month, there was “some further movement from the EU” at December’s European Council.
She said further measures would be set out ahead of the vote, which government sources say is set for 15 January.
However, the EU Commission has said there will be no renegotiation.
A spokesman said “everything on the table has been approved and… the priority now is to await events” in the UK.
Meanwhile, more than 200 MPs have signed a letter to Theresa May, urging her to rule out a no-deal Brexit – which is one where the UK leaves the EU but without any agreed arrangements covering things like how trade or travel will work in the future.
It comes as a major exercise involving more than 100 lorries is being carried out in Kent to test out how to manage traffic queues near the Channel ports in the event of a no-deal Brexit.
The PM’s deal – which covers the terms of the UK’s divorce and the framework of future relations with the EU – has already been agreed with EU leaders. But it needs to pass a vote by MPs before it is accepted.
The UK is due to leave the EU on 29 March 2019 whether the deal is passed by MPs or not.
Mrs May, who was at Alder Hey hospital in Liverpool to launch a 10-year plan for the NHS, said that after delaying the vote on her Brexit deal last month, she attended the European Council, where there was “some further movement from the EU”.
She said she had been speaking to European leaders in the intervening period.
“In the coming days what we’ll set out is not just about the EU but also about what we can do domestically, so we will be setting out measures which will be specific to Northern Ireland; we will be setting out proposals for a greater role for Parliament as we move into the next stage of negotiations,” she said.
“And we’re continuing to work on further assurances, on further undertakings from the European Union in relation to the concern that’s been expressed by Parliamentarians.”
Responding to an urgent question from Labour Leader Jeremy Corbyn, who asked for an update on progress made in achieving legal changes to the withdrawal agreement, Brexit Secretary Stephen Barclay said the Commons debate would begin on Wednesday.
He said Mrs May had been in contact with “a number of her EU counterparts” over Christmas and said ministers “will be clear on Wednesday” what developments have been made.
“Securing the additional reassurance that Parliament needs remains our priority,” he told MPs. “It’s a good deal, it’s the only deal, and I believe it is the right deal in offering certainty for this country.”
But Mr Corbyn called Mrs May’s deal a “Frankenstein monster of a deal”.
“We’re now told, if we don’t support it, the government is prepared to push our whole economy off a cliff-edge,” he said.
The prime minister’s deal is facing opposition from many of her own MPs, as well as Labour and other opposition parties including the Remain-supporting Liberal Democrats.
The DUP – which Mrs May’s Conservative Party relies on for a majority in Parliament – has said it will not back the deal.
But Brexit minister Kwasi Kwarteng dismissed suggestions that the government had accepted it would lose next week’s vote and was planning on returning to Brussels.
“The plan is to win the vote,” Mr Kwarteng told BBC Radio 4’s Today programme, adding that a week was “a very long time in politics” and he was “very hopeful” the deal would be voted through.
Fellow minister Margot James also urged MPs to back the deal but warned, if they could not reach agreement, Brexit might have to be delayed to allow for more negotiations.
“We have very little time left,” she told the BBC’s Politics Live. “We might have to extend Article 50. But I think it’s very unlikely Parliament will actually stare down the barrel of that particular gun.”
Meanwhile, writing in the Daily Telegraph, ex-Foreign Secretary Boris Johnson said the option of leaving the EU with no deal was “closest to what people actually voted for” in the 2016 EU referendum.
And Tory MP Damian Green – also an ex-cabinet minister – said the onus was on MPs to say what deal they would support.
Tory Dame Caroline Spelman, who organised the MPs’ letter with Labour MP Jack Dromey, said “crashing out” of the EU without a deal would cause job losses.
Dame Caroline – a Remain supporter who was environment secretary for two years when David Cameron was prime minister – told BBC Radio 4’s Westminster Hour programme that 209 MPs had signed the letter.
Asked if the prime minister “gets it”, Dame Caroline said: “Yes, I definitely think she gets it. She wouldn’t have invited us to come in and see her if she didn’t.”
Dame Caroline said the signatories to her letter included Brexit and Remain supporters – but the letter did not bind them to supporting the PM’s withdrawal deal.
Instead, Dame Caroline said, it created a “platform” which would “stabilise the economy and give reassurance to manufacturing”.
“We are united on one thing – we want to protect jobs and livelihoods by making sure we don’t crash out without a deal,” she said.
The MPs have been invited to meet the prime minister on Tuesday.