Pro-People’s Vote campaigners are to target 25 seats across Britain they believe, if won, could “stop Boris Johnson's bid for total power”.

One of the 25 is the Tory-held constituency of Ochil and South Perthshire.

A new organisation, Vote for a Final Say, will be working with young activists from For our Future’s Sake to support Labour, Liberal Democrat and SNP candidates in the constituencies that it believes look set to determine the General Election.

The pro-referendum campaign pointed out that all the seats were currently balanced on a knife-edge but that many voters remained confused or were being misled about which candidate was best-placed to beat the Conservatives.

The 25 constituencies have been selected after a detailed analysis recent polling and election results.

One piece of research revealed large numbers of Remain supporters are at risk of wasting their vote on third-placed candidates, ensuring that a hard-Brexit Conservative is elected in these key seats.

Another key group identified are voters – including young people, working class women and ethnic minorities – who are the least likely to participate in elections but can be mobilised when it becomes clear that the stakes are so high.

Vote for a Final Say said it had already raised enough money to spend thousands of pounds in each seat on advertising aimed at these key sections of the electorate. Over the next few days a series of national initiatives and events would be announced, it added.

James McGrory, former director of the People’s Vote campaign and a senior adviser to Vote for a Final Say, said: “Time is running out to stop Boris Johnson getting a landslide.

“There have been too many arguments about who has the best tactical voting website or polling data and not enough action. We can all agree that these 25 seats are critical if we’re to prevent Brextremist Tories securing total power. Now is the time for everyone to roll their sleeves up and start fighting back,” he declared.

The 25 target constituencies include not only Ochil and South Perthshire but also Bury North, Cambridgeshire South, Canterbury, Cheltenham, Finchley & Golders Green, Portsmouth South, and Wimbledon.