The Conservative leader, David Cameron, suffered a serious blow to his hopes of lifting the Tories at next week's conference with a poll showing his party has thrown away a seven point lead over Labour.

The poll, by YouGov, showed a Conservative lead last month had been wiped out, putting the Tories and Labour neck and neck on 36 points each. The poll for The Daily Telegraph also showed a majority do not know what he stands for.

The findings, on the eve of Mr Cameron's keynote speech tomorrow underlining his plan for changing the appeal of the Tories, were a shattering blow to his strategy. They will fuel pressure by Conservative right-wingers for a return to trusted Thatcherite themes of tax cuts, tough immigration policies and a focus on law and order.

John Redwood, who was appointed by Mr Cameron to head a Conservative task-force on competitiveness, will break ranks on Monday by calling for big tax cuts in a pamphlet published by the Thatcherite No Turning Back Group.

Mr Cameron's leadership ratings have also slumped, with the proportion who think he is a good leader falling 46 per cent to 35 per cent. Perhaps the most damaging result is that 54 per cent agreed that it "is hard to know what the Conservative Party stands for at the moment".

Mr Cameron's aides said he is determined to show the party has changed at the Bournemouth conference, which is being held under the theme of "a new direction". He will have to hold his nerve in the face of inevitable criticism: the speakers read like a guest list for BBC Newsnight. Lady Thatcher has not made the list, but platform speakers will include the author Jeanette Winterson, the rights activist Shami Chakrabarti and the feminist Rosie Boycott.

Meanwhile, Mr Cameron is about to engage with the power of the internet through his own website, featuring video weblogs of himself. The site, www.webcameron.org.uk, will provide clips of him speaking to camera. The first broadcast is reported to show him doing the washing up.