Jeremy Corbyn has called for Boris Johnson to resign after the Supreme Court found his decision to suspend Parliament unlawful.
In a keynote speech - delivered a day early following the historic ruling - the Labour leader slated the Prime Minister, calling him "unfit" to be in Number 10.
"Boris Johnson has been found to have misled the country. This unelected Prime Minister should now resign," he told Labour Party conference delegates.
Chants of "Johnson out" rippled across the conference hall following his demand for a resignation.
Mr Corbyn continued: "That would make him the shortest serving Prime Minister in British history, and rightly so. His is a born-to-rule government of the entitled, who believe that the rules they set for everyone else don't apply to them."
The Labour leader used the speech to set out his plans for a general election, which he maintained would happen once a no-deal Brexit was taken "off the table".
"Let me send this message to Boris Johnson. If you still lead your party into an election, we know your campaign will be swimming in cash, but we have something you haven't - people in their hundreds and thousands," he said.
"We will meet you head on with the biggest people-powered campaign this country has ever seen."
He reiterated his plans to hold a second referendum if successful in a general election, and promised to "carry out whatever the people decide".
If elected, Mr Corbyn said he would a negotiate a deal with the EU within three months, including a new customs union and close single market relationship.
This deal would then be offered up in a public vote, alongside the option to remain.