The government has rejected a string of key amendments to soften its Brexit terms ahead of Commons showdown over its flagship legislation.
Theresa May sought to win over Tory rebels by offering a 28-day breathing space if parliament votes down her Brexit deal, but ruled out concessions won in the House of Lords over keeping Britain in the customs union and the single market.
MPs are gearing up for a fraught two-day battle over the EU (Withdrawal) Bill next week, after rebel peers from all parties inflicted 15 defeats on the government last month.
In a sign of clashes ahead, ministers have only accepted one of the 15 changes to the proposed legislation, with a watered-down version of demands for a meaningful vote on the final deal.
Labour said it was vital that MPs had proper vote on the exit package and challenged the government to be “ready for a fight”.
The prime minister attempted to head off a revolt by holding crisis talks with pro-EU rebels in her party, such as Anna Soubry and former chancellor Ken Clarke, before jetting off the the G7 in Canada.
In a plea to Tory MPs, Ms May told reporters accompanying her on the trip: “I hope what everybody will see when they come to vote next week is the importance of ensuring that we get the EU (Withdrawal) Bill onto the statute book because it’s that EU (Withdrawal) Bill that ensures that we’re able to have that smooth transition when we leave the European Union.”
She also set out the importance of the long-delayed trade and customs bills, which will return to the Commons in mid-July after months of speculation.
Ms May said: “I have been clear about the issue of the customs union and why I think it’s important that we are not in a customs union in the future but also I have set out – and this is what we are working towards – our objectives in terms of the future customs arrangement we have with the EU which is the ‘no hard border’ between Ireland and Northern Ireland, as frictionless trade as possible between the UK and EU and able to pursue an independent trade policy which is important for that bright future.”
Alongside the toned-down version of the meaningful vote, ministers were prepared to concede on bid to allow continued participation in EU agencies and tweaked several other amendments on the Northern Irish border and family reunion for lone child refugees.
Under “ping-pong”, where bills can bounce between the two chambers, the withdrawal legislation will go back to the Lords on June 18.
Peers expect around eight or nine issues to return and are pushing for the chamber to be given an extra day for debate.
Shadow Brexit minister Jenny Chapman said: “We will look at these amendments in detail over the coming days. But, if this is the best the Government can offer then they should be ready for fight.
“There is a majority in Parliament for a customs union and a truly meaningful vote. Parliament, not the Cabinet, should decide the terms of the UK’s exit from the EU.”
A Department for Exiting the European Union spokesman said: “Our amendment removes Parliament’s ability to direct the Government in relation to negotiations, which would set a huge constitutional precedent in terms of which branch of the state holds the prerogative to act in the international sphere.
“It would also prevent the Government from demonstrating the flexibility necessary for a successful negotiation.
“The British people voted to leave the EU and we will deliver on their instruction. There can be no attempts to remain inside the EU and no attempt to rejoin it.”