The biggest threat to the prime minister is actually a defeat on the motion itself.

Brexit hardliners are threatening to rebel as they believe it commits the prime minister to ruling out a no-deal Brexit.

The motion asks the House to endorse the results of the recent Brexit votes. But the problem is MPs voted not only to authorise the PM to go back to Brussels and seek a replacement for the Irish backstop, but also for a non-binding motion which would rule out a no-deal outcome.

Leave-supporting backbenchers from the European Research Group fear that this would effectively mean signing up to a bar on no-deal.