TRADE union leaders are drawing up a shopping list of policy demands - including tax hikes for the middle classes - in exchange for rescuing Labour from bankruptcy.
Senior union figures are highlighting 'cuddly' measures such as more flexible working rights and free school meals for all primary school children.
But behind the scenes they are also pressing for new rights to strike - and, most explosively, National Insurance hikes for middle earners.
The GMB union is understood to want the upper earnings limit on National Insurance to be abolished, making higher earners pay far more.
National Insurance is charged at 11 per cent on an employee's income between ?5,460 a year and ?40,040 a year, and 1 per cent on anything earned above that.
Gordon Brown will fiercely resist such a move as electoral suicide. But the unions are ready to flex their muscles at a time when the Prime Minister is politically vulnerable and the Labour Party is in desperate financial straits.
Gifts from individual supporters have collapsed in the wake of the cash-for-peerages affair and Labour's catastrophic slump in the polls.
With Labour almost totally reliant on them for funding, the unions want to push for a detailed list of policies in crunch talks with ministers next month.
Labour has had its annual accounts signed off by auditors and they have now been sent to the Electoral Commission for publication.
The figures will show that the party remains about ?20million in debt.
Party sources insisted the role of the unions in keeping the party solvent had been 'massively overstated'.
Instead, a string of wealthy businessmen who loaned the party millions of pounds are understood to have agreed not to call in their money now.
One party source insisted: 'As for this so-called list of union demands, it's made abundantly clear to anybody that gives us money that they don't get anything in return except a greater possibility of a Labour government.'
The unions are proposing several measures designed to appeal to Labour's core vote.
Unite, the largest union, suggests that employees are given more rights to flexible workplace leave.
The public services union Unison wants all primary school children to get free school meals and the GMB wants to instal environmental workplace 'shop stewards' to encourage green workplaces.
The GMB - headed by general secretary Paul Kenny - has already voted to cut funding to a third of the 108 Labour MPs it sponsors, saying they have failed to back its policies.
Union leaders are said to be wary of explicitly demanding traditional workers' rights at this stage, for fear of unnerving the Government ahead of next month's talks.
But Unite, which gave ?2million earlier this year to Labour, is also said to be preparing a campaign to overturn the ban on secondary strike action, which was introduced by Margaret Thatcher.
Other possible demands include a provision enabling unions to ballot their members by phone or email.
Yesterday former Labour Party treasurer Baroness Prosser warned the party's finances were 'a worse situation than we have been in ever'.
She claimed some donors had abandoned the party because they were only prepared to support 'something that's a winner'.
Lady Prosser said Mr Brown was 'not exactly a sunbeam' but insisted there was no alternative leader who could attract more donors.
