Gordon Brown faces the biggest NHS strike in more than two decades just weeks after he is expected to take over as prime minister, as Unison is today set to become the second healthcare union to back industrial action over pay.
The Labour-affiliated union will attempt to exert maximum pressure on the expected new Labour leader following a motion tipped to receive overwhelming support at Unison's annual health conference in Brighton.
Nurses, occupational therapists, administrative workers and auxiliary staff are furious over the government's move to stage their 2.5% pay award over six months, which the union says reduces the value of the overall increase to just 1.9%.
It follows the decision by the Royal College of Nursing, whose members last week overwhelmingly backed industrial action over the decision.
The backlash from one of the government's most loyal union allies could take place within weeks of Tony Blair's departure, leaving Mr Brown as the expected future leader to face massive industrial rest early in his tenure.
Unison has also scheduled a national demonstration against further privatisation and marketisation in the NHS on October 13.
Karen Jennings, Unison's national secretary for health, said the union's 450,000 healthcare members found the stalled pay increase "insulting".
Speaking ahead of today's vote, Ms Jennings said: "If there is no movement by this government, the direction of travel is quite clear. We will be balloting our members and the strength of feeling is so strong we are pretty sure we are going to get the response we are anticipating [in today's vote].
"The mood is developing right across the health service."
Ms Jennings said healthcare unions would orchestrate their ballots, to ensure maximum impact. They are likely to coincide with the Labour leadership and deputy leadership election.
"This is a window of opportunity," said Ms Jennings. "We are very clear we want to influence whoever the new leader is and there is still time before the next general election for the new leader to put this right."
A government minister was barracked by Unison members yesterday as he tried to defend the government's policies on the NHS, including pay.
Hilary Benn, the international development secretary and a deputy Labour leadership contender, was forced onto the back foot by delegates who accused the government of running a campaign to privatise the health service.
The hostile reception is a foretaste of the rough ride health minister Andy Burnham is expected to receive over pay and healthcare reforms when he makes his address to the Unison conference on Tuesday.
Platform speakers pointed to a series of reports which found that privatisation - such as independent treatment centres - were inefficient and wasteful.
Delegate Martin Booth told the conference: "Whatever Mr Benn or any other government minister says, there are whole areas of the NHS in serious crisis because of this government's determination to privatise and marketise the NHS."
Attempts to suspend funding to the Labour party over NHS policies yesterday failed to receive the backing of the 1,000 members attending the three-day conference.
