The poll placed the Tories one point down, on 32 per cent. Meanwhile Labour fell four points to trail on 26 per cent.
Lib Dem leader Nick Clegg has been riding high on a raft of polls that show his party gaining significant ground after he was crowned as the winner of Thursday’s leaders’ debate.
If the figures were repeated at the general election, there would be a hung parliament with Labour as the biggest party, meaning Gordon Brown would likely try to forge some kind of Lib-Lab coalition.
The Tories will this week attempt to discredit Liberal Democrat policies in a bid to reverse the sudden surge in the third party’s popularity.
One Tory strategist said yesterday: “Their manifesto is soft on crime and is Europhile. It’s completely out of step with what the average punter thinks.”
The Tories are also warning voters that they might “vote Clegg, but get Brown” if they vote for the Lib Dems.