>WHY DOES THIS AMERICAN ACTOR SUDDENLY CARE ABOUT EU??
The People's Vote drive aims to unite anti-Brexit groups, with a rally being held in Camden, in London on Sunday.
Actor Sir Patrick Stewart, who backs the campaign, said that if people voted to reject the exit deal, the UK would "simply stay" in the EU.
Both the Conservatives and Labour have ruled out a second referendum.
Britain voted to leave the EU by 51.9% to 48.1% in June 2016.
The UK will formally cease to be an EU member in March 2019, and the two sides hope to reach a deal by October in time for it to be ratified by UK and European parliaments.
Sir Patrick told the BBC's Andrew Marr show that the "terms and conditions" of Brexit were "quite unlike" how they were presented during the run up to the 2016 referendum.
The People's Vote campaign would argue that the public, not MPs, should get the final say on Brexit, he said.
He also said he was motivated by "history and emotion" to want to stay in the EU.
"I'm a war baby and growing up a lot of the world was not good. So the day we joined was one of the most exciting days of my adulthood," he added.