A major campaign will target more than 60 seats to oust Conservatives by tactical voting, in order to build a Commons majority among progressive parties. Campaigners behind the drive are warning that Labour’s current poll lead is on “weak foundations” and the party must have a strategy for power sharing. The Win As One campaign from the thinktank Compass will campaign for candidates in 62 seats dubbed a “progressive tragedy” – where the combined progressive vote outnumbered rightwing parties but delivered a Conservative victory. The group will also prioritise candidates who are backing electoral reform and proportional representation. Labour conference in September overwhelmingly backed a motion calling on the party to embrace a proportional electoral system, though there is no guarantee the proposal will be in the party manifesto. Key allies of Keir Starmer are deeply unconvinced by the reforms and believe they would jeopardise future Labour victories and act as a distraction before the next election, which could be fuel for Tory attacks. Starmer is particularly keen for the party to give no quarter to any suggestion it could do a deal with the SNP, because of the party’s campaign in Scotland and the damaging Tory attack from 2015. Launching the campaign in the Guardian, Compass said fresh data shows that even the current healthy poll leads for Labour may deliver only a hung parliament or a small majority for Starmer. In polling for Compass, voters also appear to reject the idea that electoral reform should not be a priority and are in favour of parties working collaboratively. Compass has previously championed a progressive alliance of parties at general elections, where Labour, the Lib Dems and the Greens stand down in favour of each other to have the best chance of defeating the Conservatives. The survey, commissioned by Compass to mark the launch of the campaign, and to tie in with the three-year anniversary of the 2019 Tory landslide, reveals deep dissatisfaction with our political system, suggesting any future Labour government working alone would face a huge uphill battle to tackle the big challenges of our time. The YouGov poll shows 63% of the public think Labour’s poll lead is largely against the government, with only 11% saying it is based on support for the party itself. Compass said that analysis of the current polling data predicts that a 28% Labour poll lead now would probably result in an 8% lead at the election itself. It said Labour would also need a bigger swing than in 1945 or 1997 to win a majority and that boundary changes and new rules on voter ID were also likely to affect Labour votes. The poll for Compass found 73% of voters believe the political system mostly serves the rich and the powerful and 71% say it does not work for ordinary people. It also found that 63% believe the current system “puts too much power in the hands of a small number of swing voters”. It also found widespread support for tactical voting – 71% of those who say they will vote for progressive parties at the next election would support an electoral alliance that would result in candidates standing aside for the best placed progressive candidate to beat the Conservatives. Proportional representation has less support, but still a majority of votes, with 56% of people backing a change to the voting system. Neal Lawson, Compass’s director and spokesperson for Win as One, said: “There is now an undeniable demand from the country – not only for a new government, but a new political system. “This polling stands as a clear warning and lesson to a Labour party that is refusing to back [proportional representation] and unwilling to work with others. This poll shows overwhelming voter dissatisfaction with the way the two-party system is failing. Ignoring this risks putting the party on the wrong side of the public – and history.” The campaign will be aimed at England and Wales and makes the case that smaller parties such as the Greens must be incentivised to take part and that tactical voting advice must be rooted in local issues.