British politicians opposed to Brexit will begin launching a fightback on Tuesday.
More than 200 are calling on the prime minister to ensure a no-deal Brexit cannot happen, while a parliamentary vote is planned which could force a second referendum.
There is growing pressure on the leader of the main opposition party, Jeremy Corbyn, to back a rethink on leaving the European Union at all.
Al Jazeera's Laurence Lee has been speaking to Labour party activists who feel betrayed by their own leadership.
