Gordon Brown is to face an unprecedented leftwing attack on his policies as well as the threat of damaging strike action in the run-up to the May elections, Guardian Unlimited has learned.
Mark Serwotka, the general secretary of the Public and Commercial Services union, plans to place the chancellor at the centre of a high-profile campaign against the government's cuts and privatisation agenda in the civil service.
"Our issue with Gordon Brown is that the policies he has pursued we think are disastrous and it is an appalling way to treat his own workforce," Mr Serwotka said.
The union is planning a series of hustings in areas with high numbers of residents working for the civil service, where election candidates will be grilled on the 84,000 job cuts taking place as part of the government's efficiency review.
The campaign will seek to expose whether or not local candidates will disavow Mr Brown's policies.
The move will prove a political headache for Mr Brown at a time when he is seeking to boost his credentials in preparation for the leadership contest expected after the May elections.
To add to the chancellor's woes, the decision comes ahead of a ballot result that is expected to confirm backing for continuous industrial action next week.
It will begin with a one-day national strike to coincide with the closing date for annual tax returns at the end of this month.
Mr Serwotka, whose union is not affiliated to the Labour party, has been one of Mr Brown's most vocal critics, blaming him for the policy decisions that have directly affected civil servants.
The chancellor, who is widely expected to become prime minister later this year when Tony Blair steps down, triggered further alarm when he announced in his pre-budget report in December that he wanted a further 15% of efficiency savings to be found between 2008 and 2011.
The PCS has repeatedly argued that the scale of job cuts is damaging service delivery, and has condemned the government's move to deliver the bulk of services for the country's most vulnerable groups through call centres.
The union has also campaigned against the privatisation of key employment services outlined in the Department of Work and Pensions white paper, which would see voluntary and private companies take over tranches of work previously carried out by civil servants.
Mr Serwotka said he expected this latest campaign to have most impact in Scotland and Wales.
The Welsh-born general secretary said job cuts in Wales had hit rural communities where alternative employment is harder to find.
He pointed to the irony that a country ranked poor enough to receive objective one status funding from Europe was losing public sector jobs as a result of policies being made in Westminster.
"We have a chancellor based in Westminster making decisions impacting heavily in Wales and Scotland that are in the opposite direction to [where the devolved governments] in Wales and Scotland want to go," Mr Serwotka said.
The Guardian revealed last week how government policies have divided Labour policitians when they impact adversely on local services.
Thirteen cabinet ministers have campaigned locally against NHS closures over the past few months, including Hazel Blears, Labour party chairwoman.
"Labour MPs are happy to say yes, this policy is great but when it looks as if it has a consequence in their constituency they feel differently," Mr Serwotka said.
"I thought Hazel Blears' actions said something. It is a case of not in my back yard."
The leftwing union leader denied he was trying to destabilise Labour, claiming the political campaign was non partisan.
"We are trying to say to all politicians standing in the elections that they are going to have to come clean on where they stand on these issues.
"We are doing that to try and make people face up to the consequences in their constituencies and their wards. Is that a threat to the Labour party? It is not a threat to the candidates who stand up to be counted."
Seventy five MPs are in the crossparty PCS parliamentary group, chaired by Labour's John McDonnell, who has already signalled his intentions to stand against Gordon Brown for the Labour leadership, and campaigns fiercely on keeping public services out of private hands.
The union's ballot result for continuous industrial action closes next week and will begin on January 31 unless the government guarantees a policy of no compulsory redundancies for civil servants to achieve further cuts, and provides safeguards for members transferred to the private sector.
The union is also calling on the government to deliver a promise made by Mr Blair three years ago to streamline the 229 pay negotiations which currently take place within the civil service and result in wildly different levels of pay.
Mr Serwotka said he "very confident" that the union's 280,000 civil service members would vote in favour of a national strike because of the fury felt over cuts and privatisation.
The union voted for a political fund which will be launched this April.
