Tories offer first-time home buyers a £2,000 sweetener with pledge to waive stamp duty

David Cameron pledged populist tax breaks for first-time home buyers as he challenged Gordon Brown to "stop dithering" and call a general election.

The Tory leader struck a defiant tone as his party began gathering for a crunch conference in Blackpool, despite persistent sniping in his own ranks and a double-digit deficit in some opinion polls.

Mr Cameron made the first attempt to turn the tide back in his favour, promising a manifesto pledge to abolish stamp duty for first-time buyers on homes worth up to £250,000.

The Tories claim the move would mean nine out of 10 would-be home owners will not pay the levy, saving an average of £2,000 for some 285,000 people.

The policy will please traditionalists who have been demanding firm commitments to tax cuts, as well as appealing to the generation of young people frozen out of the property market by soaring prices.

Mr Cameron said the idea showed the Conservatives were the "party of aspiration, giving you power and control over your life".

The move to a more traditional vote-winning tax policy came as a new poll reveals that controversial green taxes proposed by Mr Cameron are overwhelmingly popular. And the series of levies put forward by Zac Goldsmith are even more favoured by Conservative voters than the general public.

The poll of 2,015 people, to be published tomorrow by Ipsos Mori, records up to two-thirds majorities for the proposals, drawn up this month by a policy group co-chaired by the radical millionaire green activist.

The extent of the support, which is surprising even senior Conservatives, will come as a timely relief to Mr Cameron, whose green agenda has come under vigorous attack in the run-up to his party conference, which opens today.

It is also a sharp setback to his critics. Last week, the hard-right Lord Tebbit denounced his policies as "unpopular" and even George Osborne, Mr Cameron's closest political ally, attacked the party's "uber-modernisers" who had made the environment their cause.