The former Home Secretary Amber Rudd has appealed to Conservative colleagues to support Theresa May when the Commons votes again on the EU withdrawal bill.
In a show of unity, Remainer Ms Rudd has co-authored a piece in Sunday’s Telegraph with Brexiteer Iain Duncan Smith, calling on MPs to back the PM.
Backing the bill was a “no brainer” and vital to delivering Brexit, they said.
Labour are urging Tory rebels to side with them on “defining” issues such as staying in some form of customs union.
The bill returns to the Commons on Tuesday and Wednesday as ministers try to overturn more than a dozen amendments made by the House of Lords.
If enough Tory MPs decide to vote with Labour and other opposition parties, the government could be defeated on several key votes.
More than a dozen rebels could vote in favour of amendments intended to keep the UK in a customs union with the EU and give Parliament a decisive say over the final Brexit deal.
While rebelling would be “difficult”, Labour’s Sir Keir Starmer said Tory MPs had a “real chance to change the course of the Brexit negotiations” and “bring order” to what he said had become a chaotic process.
‘Unity of purpose’
But Ms Rudd and Mr Duncan Smith said Labour, which has been criticised by some of its own MPs for not backing an amendment on single market access, would be quick to exploit any government setback.
“Jeremy Corbyn will do everything he can to stop us,” they wrote. “That includes cynically trying to frustrate the Brexit process for his own political ends.”
In the joint article, the pair say the withdrawal bill is “not about competing visions of the future but about ensuring legal certainty at our point of departure”.
Urging colleagues “to demonstrate discipline and unity of purpose”, they said “we cannot allow ourselves to become divided and risk losing the precious chance to go on implementing policies that transform lives”.
Ministers are confident of winning most of the votes, as Mrs May will have the support of a handful of pro-Brexit Labour MPs and the backing of 10 Democratic Unionist MPs.
But they are vulnerable to defeat on the terms of “meaningful vote” that Parliament is to be given on the final deal.
Labour and some Tories want MPs to have the final say on what to do next if the deal is rejected, including the power to force ministers to go back to the negotiating table.
Speaking to the BBC’s Andrew Marr show, Cabinet Office minister David Lidington accepted the parliamentary arithmetic was “difficult” for his party as they do not have a majority in the Commons.
He urged MPs to get behind the PM, insisting that Mrs May would “not shirk from being tough” as negotiations come to a head in the run-up to a summit of EU leaders later this month.
He sought to down play cabinet divisions and defended the Treasury, described as the “heart of Remain” by Boris Johnson in remarks last week, saying chancellor Philip Hammond was “working extremely hard” to deliver on the referendum result in a way that protected jobs and economic growth.
The prime minister, who will address all Tory MPs on Monday, has accused peers of going “far beyond” their role with their amendments to the withdrawal bill.
Speaking in Canada before leaving the G7 summit, she said: “Let’s remember what the withdrawal bill is for: it’s about delivering a statute book that is ready for Brexit day.”
“This government is delivering on the decision made by the country in the referendum to leave the EU and we will not accept anything that prevents us from taking back control of our money, laws and borders.”
But confirming her party would vote against the government, Scottish First Minister Nicola Sturgeon said the EU Withdrawal Bill as it stood was “unacceptable”.
She said her MPs wanted a vote on “protecting the powers” of the Scottish Parliament after the UK leaves.
“We are getting close to crunch point,” she said. “The government risks taking the UK off a cliff-edge.”