The director of a website set up to encourage tactical voting yesterday predicted that the Conservatives could be pushed into third place after a "massive ground-swell of anti-Tory interest".
Over the past few days more than 50,000 voters have contacted a number of websites targeting more than 150 constituencies where the Tory candidate is vulnerable to "vote-swapping". One of the sites - www.Tacticalvoter.Net - has attracted more than 150,000 hits since the campaign began.
A further six regional websites, including one launched by singer Billy Bragg in Dorset, are also advising people how to vote tactically to defeat Tory candidates.
Mr Jason Buckley, Director of Tacticalvote.Net, said: "It only needs 280,000 voters in 84 constituencies to reduce the Tories to a rump party and propel the Liberal Democrats into second place and with tactical voting this is now on the cards. A small number of voters working outside the official party structures can create a huge upset. Tactical voting will build and build until either the Tories or the electoral system breaks."
Mr Buckley (27), from Chelmsford in Essex, has never taken part in any political activity before but said he became interested in tactical voting last year after feeling "disgust" at Conservative attacks on asylumseekers.