Gordon Brown will warn voters not to "wreck the recovery" in a New Year's message setting out the political battlelines ahead of 2010's general election.
The Prime Minister, who polls suggest faces an uphill struggle to cling on to power, will promise to publish a blueprint to "really get Britain moving again".
In a webcast for the Downing Street website, he will set out an optimistic assessment of the country's prospects for economic recovery in the next 12 months.
But, echoing recent attacks on the Tories as elitist, he will warn against "a decade of austerity and unfairness where the majority lose out while the privileged few protect themselves".
Only Labour policies would ensure "the people on middle and modest incomes who don't want any special favours" benefited as well, he will say - according to extracts released in advance.
The message puts economic recovery at the top of a list of resolutions for 2010 that also includes "radical" public service reform, "a new cleaned up politics" and tackling terrorism.
And it includes a promise to publish later this week the first part of a "prosperity plan for a successful, fairer and more responsible Britain" - including investment in high-speed rail, aerospace, the digital economy, clean energy and other "industries and jobs of the future".
Mr Brown, who has faced some criticism from within his own ministerial ranks for what is perceived as a bid to launch a "class war" battle with Eton-educated David Cameron's Conservative Opposition, will include a direct appeal to the party's core vote.
"There are some who say we must plan for a decade of austerity and unfairness where the majority lose out while the privileged few protect themselves," he will say.
"I believe we can create a decade of shared prosperity - with opportunities fairly shared among all those who work hard and play by the rules."