Mr Brown is expected to use his Bournemouth address late on Monday to focus on the key themes of health, education and crime.
But his repeated failure to answer questions about the likely date of a general election in interviews with the BBC and Sky News on Monday morning has further fuelled speculation.
The prime minister told the BBC: “I’ve got a programme of change for the future. Do I need to call an election to do so? No. The right thing to do is to get on with the job”. He claimed that the public wanted to hear “what we are offering for the country, and anything that diverts from that is not fair to the British people”.
He also confirmed he had no plans for a referendum on the EU constitutional treaty.
On Sunday night, The Sun released an Ipsos/Mori poll showing Labour with an eight-point lead, three up on the previous Mori poll.
Labour was on 42 points, the Conservatives on 34 and the Liberal Democrats down to 14.
In a pointed stoking of the atmosphere, Mr Brown’s aides also released a six-page letter setting out the prime minister’s vision to the party’s national executive, billing the document as "a draft of the manifesto”.