BORIS Johnson could be denied a Commons majority if just one in three Remainers vote tactically, a mass anti-Brexit study has found.
The Best for Britain group has launched a website telling Remain voters which party to back in their constituency in order to stop the Tory or Brexit party candidate from winning.
The pro-Remain tactical voting website also threatens to remove Mr Johnson himself from his own West London seat of Uxbridge and Ruislip if the Lib Dems and Labour work together.
Laying bare how powerful tactical voting could be in the December election, its analysis predicts the Tories would win a 44-seat majority without any tactical voting from Remainers.
But if just 30 per cent of Remain backers vote tactically then it would swing the election and hand Remainer parties 323 seats.
That would give them a majority in Parliament and prevent Mr Johnson from getting a Commons majority to approve his Brexit deal.
And it would enable them to plough ahead with a second referendum designed to reverse Brexit.
The research showed that if four in ten Remain voters worked tactically they could return a majority of 36.
The study It was based on seat-by-seat analysis of 46,000 people over September and October using a similar technique to one that gave a rare but accurate prediction that Donald Trump would become US president in 2016.
Backed by Lib Dem MP Sir Vince Cable, exiled Tory Dominic Grieve and Labour’s Anna McMorrin, the campaign is encouraging voters to visit getvoting.org to learn how to vote tactically.
Former party leader Sir Vince said of tactical voting: “It’s a powerful tool and we’ve got to use it.”
Tactical voting could also worry Mr Johnson closer to home.
He won his Uxbridge and South Ruislip seat in 2017 with 50 per cent of votes against Labour’s 40 per cent.
With rumours circulating that he may stand elsewhere, there is a chance that Labour or the Lib Dems may seize it from him.
But Best for Britain polling suggests an overwhelming majority of pro-Remain voters would need to vote tactically to edge the PM out.
Pollster Lewis Baston provided the PM with some optimism.
“My own view is that it will be quite hard in that seat to persuade people that Lib Dems or Labour are out of the running and therefore it’s quite a tough ask,” he said.
“I think prime ministers often get a bit of a bump in their own seat anyway so it’s a tough one.”
Tactical voting relies on the public using their own research and intuition to choose who to back to edge out a candidate they strongly oppose.
But the same result can be delivered with pacts between parties, as is occurring in Mr Grieve’s Beaconsfield constituency where he will stand as an independent, unopposed by the Lib Dems.