Around a tenth of the electorate could be prepared to switch allegiances and vote tactically at the general election next week, new polling suggests.
The survey of 10,000 voters found that 44 per cent of Labour Remain voters would back the Liberal Democrats where they are best-placed to defeat Brexit-backing Conservatives, while 39 per cent of Lib Dem supporters are prepared to do the same to help a Labour candidate beat a Tory.
Despite Boris Johnson’s overall lead in the polls, campaigners for a Final Say referendum believe tactical voting on this scale could be enough to deny him the overall majority in the Commons – scuppering his plans to force through Brexit by 31 October.
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The survey, released by the Vote for a Final Say campaign, which recently splintered from the People’s Vote group, suggests that movement in the polls during the election so far are largely explained by tactical votes, with Brexit Party supporters switching to Tories as the best means of delivering EU withdrawal and Lib Dems swinging behind Labour candidates in seats where Jo Swinson’s party stands no chance of victory.
But the poll found that Mr Johnson has “very limited capacity” to squeeze further backing from Leave supporters, who make up just 45 per cent of those likely to vote.
Former Lib Dem leader Sir Vince Cable said that the question facing voters was no longer whether his party or Jeremy Corbyn’s Labour could win, but whether Mr Johnson and his “Brexit extremists” can be prevented from seizing total power.
“We are now just days away from a general election which threatens to cast a long shadow over the future of our country and an entire generation,” said Sir Vince.
“Nobody really thinks that Labour or, sadly, the Liberal Democrats are likely to win a majority. Therefore, the only question facing voters next week is whether they want to hand total power to Boris Johnson and the English nationalists and Brexit extremists now occupying Downing Street.
“I have been out there campaigning to persuade Labour voters to support Liberal Democrat candidates in constituencies like Wells, Brecon and Wimbledon. But I also know there are a great many good Liberal Democrat voters preparing to hold their nose and back Labour in seats like Canterbury and Sedgefield – or back brave independents like David Gauke. I understand why they are doing that and recognise why it may be necessary if we are to stop Brexit being forced on us by the Tories.”
The 10,000-voter survey, conducted over the past two weeks by Populus Data Services (PDS) for the Vote for a Final Say campaign, found a tenth of the electorate could vote tactically on Thursday.
Some 53 per cent of Liberal Democrat supporters also said they would vote tactically if their favoured candidate stood no chance of victory in their constituency, with 39 per cent saying they would back Labour and 14 per cent Conservatives in these circumstances.
Among Labour Remainers, 44 per cent were ready to switch to the Lib Dems if they are best placed to win, and just 3 per cent willing to back Tories.
Shifts on this scale would protect dozens of Labour constituencies vulnerable to the Tories and ensure the Lib Dems hold onto their current seats, while improving the prospects of Mr Corbyn’s party seizing seats like Putney or Chingford and Woodford Green, and Ms Swinson’s party winning Remain-backing constituencies like Esher and Walton from the Conservatives, said the Vote for a Final Say campaign.
Pollster Andrew Cooper said it was clear from the survey that a majority of voters do not want the Tory version of Brexit to go ahead without a referendum, but also that a majority are opposed to a Labour government led by Mr Corbyn. Mr Johnson’s Tories were “cynically leveraging” voters’ fear of Mr Corbyn to win support from people who do not want the kind of Brexit they are offering, he said.
Lord Cooper, chair of Populus and David Cameron’s head of strategy ahead of the Conservatives’ 2015 election victory, said the Tories and the Brexit Party had “effectively become one”, and that the “broad-based, open-minded, aspirational One Nation Conservative Party” has now been replaced by a “narrow nationalist party” obsessed by the single issue of securing Brexit at any cost.
“The millions of past Tory voters who are appalled by this should not feel they have no choice but to go along with it,” said Lord Cooper. “They have a choice. It is not inevitable that we get a big majority Tory government that will ram through hard Brexit.”
With less than a week to go before polling day, “two plain truths” emerge from the polling, he said. “Firstly, there is absolutely no chance whatsoever of this election producing a majority in the House of Commons either for Jeremy Corbyn to be prime minister, or to pass the irresponsible and extreme elements of his agenda that worry so many mainstream voters.
“Secondly, as shown powerfully in this big new poll, if those who say they are willing in principle to vote tactically to avert hard Brexit actually do so, there is still a real chance of preventing it.”
Alastair Campbell, who helped Tony Blair to three successive Labour election victories, said it was time for Remain voters to set aside party loyalties in order to keep open the chance of a referendum.
“This election is not about Jeremy Corbyn or Jo Swinson – neither can win a majority,” said Mr Campbell. “It has come down to one simple question: do you want to give Boris Johnson and the reckless right-wing gang that surrounds him total power to do whatever they want?
“It is not too late to stop him and secure a democratic Final Say on Brexit. But a lot more people are going to have to focus on who can win their seat, hold their noses and put aside party loyalty, or even views about the respective leaders, if we are to have a real chance.”
Entrepreneur and activist Gina Miller, who is conducting a separate tactical voting campaign, said that a Conservative majority would mean that “all routes are closed” to a Final Say referendum.
Speaking to The Independent as she campaigned with the Lib Dems in the target seat of Esher and Walton, held by foreign secretary Dominic Raab, Ms Miller said: “If there is no tactical voting there will be a Tory majority. If there is a Tory majority then a referendum is gone.
“A hung parliament takes us to a second referendum. If there is a Conservative majority, all routes are closed. If there is a hung parliament then there’s a route to find a way to a second referendum.”
A separate poll by the pro-EU Best for Britain campaign also found that if fewer than 41,000 voters cast their ballots tactically on Thursday in 36 constituencies it could deliver a hung parliament.
According to the analysis, the constituencies where tactical voting mattered most included Dewsbury where just 82 Liberal Democrat and Green voters could stop the Tories seizing the seat. West Bromwich West – the seat of outgoing Labour deputy leader Tom Watson – would also require 183 Remain voters to switch to Jeremy Corbyn’s in order for the constituency to remain red.