Theresa May has caved in to pressure to publish a plan for Brexit by the end of March, but laid down a challenge to MPs to vote in favour of triggering article 50.
Labour and rebel Tory MPs declared victory after No 10 accepted an opposition motion calling on the prime minister to reveal the government’s Brexit aims before starting the formal process of leaving the EU.
The government’s move was designed to stave off an embarrassing parliamentary revolt for May, as about 20 Tory MPs had been prepared to defy her by voting with Labour.
However, No 10 insisted it had always intended to publish a Brexit plan and mounted an attempt to turn the debate to its own advantage by tabling an amendment to Labour’s motion, calling for article 50 to be triggered before the end of March.
This will ask MPs to “respect the wishes of the United Kingdom” by agreeing to the government’s timetable for Brexit, with the aim of flushing out any who do not want to vote in favour of starting the process of leaving the EU.
No 10 will also be hoping that a majority of MPs in favour of triggering article 50 will allow it to claim more of a parliamentary mandate for Brexit, although it is only a non-binding motion.
It will not be enough to satisfy legal demands if the government loses its appeal in the supreme court and is forced to publish an act of parliament before starting the formal Brexit process.
That requires full legislation to pass through both the Commons and Lords, and could allow parliamentarians to pass amendments about the type of Brexit the government will seek.
Labour and most of the Tory MPs pushing for the UK to stay in the single market in a “soft Brexit” will accept the government amendment, as they do not dispute the idea of triggering article 50.
However, they still intend to cause a headache for May during the debate by pushing for a comprehensive white paper – an official pre-legislative paper – detailing her plan for Brexit before the end of January.