Liberal Democrats have been urged to spread the message that their Conservative coalition partners "can't be trusted" to look after normal people rather than the super-rich.
A leaked script of the party's lines to take in the media urges MPs, candidates and councillors to say that only the Lib Dems are committed to building "a fair society".
It was distributed by the Lib Dem director of communications, Tim Snowball, who appealed for recipients to "communicate from this script at every opportunity".
The document will be seen as evidence of the Lib Dems' efforts to carve out a distinctive identity for themselves ahead of the 2015 general election.
It builds on Deputy Prime Minister Nick Clegg's own message in recent months that only the Lib Dems can deliver both a strong economy and a fair society.
Clegg has used his New Year message this week to say he would "anchor" the coalition in the centre-ground in 2013.
The script says Labour "can't be trusted to manage the economy", having "nearly bankrupted Britain", but it is the strident tone on the Tories that is most notable given the potential for inflaming coalition tensions.
"The Conservatives can't be trusted to build a fair society. Until the Lib Dems got into government, no one could stop the Tories from looking after the super rich who fund their party, while ignoring the needs of normal people who struggle to make ends meet."
It goes on to list Tory plans that the Lib Dems have blocked, including relaxing the law on hiring and firing employees, cutting inheritance tax and allowing schools to be "run for profit".
"Let's never go back to the way things were, because Labour can't be trusted with your money, and the Tories can't be trusted to build a fair society," it says.
"Only the Lib Dems can be trusted to build a stronger economy and a fairer society, enabling every person to get on in life."
The lines, obtained and published by the Liberator blog, was attached to a message from Snowball saying that Clegg's New Year message was "the first full external use of our new Party message script".
It is based on research on the Lib Dems' "electoral market" by Ryan Coetzee, an adviser to the Deputy Prime Minister, and consultation with "many party stakeholders".
"If we all stick to and get some volume behind this script, by this time next year our voters will know that the Liberal Democrats are building a stronger economy in a fairer society, enabling every person to get on in life," Snowball wrote.
"That Labour can't be trusted with their money, and the Tories can't be trusted to build a fair society. And also just a few of the things we have achieved in government.
"So, if you make one New Year resolution this year, please make it to help us be 'On Message, In Volume, Over Time' and communicate from this script at every opportunity."