However, if Labour, the Liberal Democrats and the Green Party were to agree to stand down candidates where this would maximise the chances of beating the Conservatives, Labour would no longer need the SNP to govern.
Labour would win 323 seats and the Liberal Democrats 13 in this scenario, meaning their combined number of MPs would exceed the 326 needed for a simple majority in Parliament.
Ahead of the 2019 general election, Nigel Farage, then the Brexit Party leader, announced that he would not field candidates in 317 Conservative seats amid concerns that doing so would enable the election of Liberal Democrat candidates if the Right-wing vote was split.
In 2017, meanwhile, Ukip did not stand candidates in North East Somerset or Shipley, constituencies represented by eurosceptics Jacob Rees-Mogg and Philip Davies.
Layla Moran, the Liberal Democrat MP for Oxford West and Abingdon, suggested people would be inclined to vote tactically at the next election and urged her party to be “honest” about where it has a realistic chance of success and where it could split Labour’s vote share.
Speaking to The Observer, which published the research, Ms Moran said: “In an election where the opposition vote is split, many voters will want to back the candidate who is most likely to win and deliver change.
“To this end, we must be honest with each other about the situation in each constituency and ensure that the voters have the information they need to lock the Tories out of power.”