Ministers are preparing for possible defeats over the government’s Brexit bill in the House of Lords next week.
Peers completed a marathon three-day committee stage debate on the European Union (Withdrawal Agreement) Bill without amending it.
But there are certain to be key votes, and possible defeats for the prime minister, when the bill returns for its report stage on Monday and Tuesday.
Contentious areas due to come under fresh scrutiny include the government’s decision to rule out any extension of the 11-month transition period to negotiate a trade deal with Brussels.
A vote also looks likely over what the opposition sees as a watering down of an earlier commitment on reuniting child refugees with families in the UK.
Critics on the Labour and Liberal Democrat benches believe Johnson has ditched pre-election compromises on protections for workers and child refugees after winning a big majority.
The bill has already cleared the Commons with big majorities for its provisions and the government has warned peers not to frustrate the “will of the people” ahead of the UK leaving the EU on January 31.
Any changes made to the legislation would need to go back to the elected Commons, where they would almost certainly to be overturned, and could lead to a bout of parliamentary ping-pong ahead of Brexit.