Health workers fighting against what they call the "marketisation" of the National Health Service have been boosted by a letter of support from medical professionals and literary figures, who warn that letting in "profit-driven international corporations" could cause the break-up of the NHS.
They include Professor David Hunter, who heads a research centre at Durham University, and Professor Rodney Reznek, one of the country's leading radiologists. Others backing the protest include the writers Nick Hornby, Philip Pullman, Claire Rayner and Claire Tomalin, and the poet laureate, Andrew Motion.
The row centres on £3bn worth of contracts now on offer, which will give thousands of NHS patients the option of receiving private treatment free of charge.
All the big trade unions are expected to throw their block votes behind the public sector union Unison, which wants all new contracts for private treatment of NHS patients put on ice. The Unison general secretary, Dave Prentis, told The Independent on Sunday: "The Government is pushing through its so-called 'reform' agenda with no debate within the party or consultations with patients and staff, no thought of the consequences and no clear vision of where it will lead."
Although they have a good chance of winning the vote, the unions may find it impossible to change government policy unless they can get substantial political backing. Mr Blair sees health reforms as central to his strategy for holding the centre ground of British politics, retaining the support of voters who might be tempted to switch to the Tories when their new leader is in place.
The Prime Minister is determined to resist pressure to take Labour to the left, to win back support lost to the Liberal Democrats. He does not want the conference to be distracted by arguments over Iraq, or speculation about the date of his departure.
He will give Iraq only a passing mention in his big conference speech on Tuesday - and may not even refer to his resignation at all - but will talk at length about why reforms in health and education must go ahead, despite union objections.
He is expected to say: "There's a great myth that we don't have a market in services now. We do. It's called the British public school system and private healthcare - but it's only open to the wealthy. There is another myth: choice is a New Labour invention. Wrong - choice is what wealthy people have exercised for centuries.
"It is true we are trying to create a market in public services. But one with this fundamental difference: in public services, when we give choice but maintain the service free at the point of use, wealth is irrelevant."
The Secretary of State for Health, Patricia Hewitt, will argue in a pamphlet that bringing competition into healthcare is consistent with the ideals of the founder of the NHS, Aneurin Bevan.
Yesterday, the Cabinet Office Minister, John Hutton, accused the health unions of "peculiar and dishonest manoeuvring" aimed at undoing the manifesto on which Labour fought the May election. "The peculiarity is seeing the unions line up with consultants who have benefited from long NHS waiting lists because they drive people to pay for treatment," he said.
Ministers will give equally short shift to a resolution from another big union, the TGWU, which wants to amend trade union laws passed by the Conservatives in the 1980s, to strengthen the hand of employees working for contractors such as Gate Gourmet, which provides catering for BA. Current law prevents the unions from picketing BA in support of better pay and conditions for Gate Gourmet workers. Ministers will block anything that looks like a licence for 1980s-style mass pickets.
Mr Blair's supporters have dismissed suggestions that this could be his last conference as Labour leader, although dissenting voices are calling on him to go quickly.
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