Jeremy Corbyn has pledged to work across party lines to prevent Boris Johnson from suspending Parliament when it returns on Tuesday.
The Labour leader said MPs will pursue legislative means to stop the Prime Minister and avert a no-deal Brexit.
“We will be back in Parliament on Tuesday to challenge Boris Johnson on what I think is a smash and grab raid against our democracy,” he said.
“He's trying to suspend Parliament in order to prevent a serious discussion and a serious debate to prevent a no-deal Brexit.”
Mr Corbyn said the implications of a no-deal Brexit are “very serious” and would mean trade and jobs would be “immediately at risk”.
He remained confident there was enough time to introduce legislation to prevent the Prime Minister from proroguing Parliament.
“I had a very constructive meeting with the leaders of all the opposition parties in my office a couple of days ago to go through these and we're going to do everything we can to ensure that Parliament is able to assert itself on behalf of the British people,” he said.
Earlier in the day Mr Corbyn said a future Labour government would not make another Scottish independence vote a priority.
“I want there to be a Labour government in this country and I want that Labour government to be able to deliver for the people of Scotland as for the rest of the UK,” he said.
“In the early years we would be asking very strongly for this not to be put forward as a priority.”