It's no good Tony coming and getting the tone right and not really giving us the commitments we need

Dave Prentis Unison

Mr Blair has already strived to ease fears over the plans in an interview ahead of the speech but some of the larger unions are threatening to wage a national campaign against the proposals.

Dave Prentis, general secretary of Unison, said in an interview on BBC News Online that one speech would not solve the problem and a massive effort was needed to raise public servants' morale.

Reform to deliver

In his speech, the prime minister is likely to defend the government's record on public services.

He says there are now more people employed in the public sector than when Labour first came to power, and pay is increasing faster than in the private sector.

John Monks says the prime minister will be courteously received

He will also argue that the UK is the only country increasing spending on health and education this year.

He will stand by his proposals for making the most of the private sector, arguing they are a means of producing modern, quality public services.

In an interview with The Guardian on Tuesday, Mr Blair said: "I believe strongly in the public service ethos; that is why I am trying to reform and deliver better public services, not privatise them.

"The notion that either the government has gone anti-public or is privatising public services is fatuous."

He also warned firms they would not be allowed to increase profits at the expense of former public sector workers.

'Last chance' speech

The TUC conference has already been dominated by the issue of the public services, and threats of industrial action to combat what many union members and leaders see as creeping privatisation.

GMB union leader John Edmonds said Mr Blair's speech was his last chance to "step back from the brink" of conflict with the unions over increased private involvement in the public sector.

"We don't want a pat on the head or warm words," he said.

Clarke: Blair not looking for a confrontation

"We want concrete assurances that ministers will abandon their dogmatic obsession with privatisation."

Unions have complained about the lack of detail about the plans and Unison's Dave Prentis said "more meat on the bone" was needed in tough negotiations with ministers, which must conclude quickly.

"We have got four years before the next election and if we waste two years in conflict then the improvements we all want will not come on stream before the next election," he told BBC News Online.

He urged Mr Blair to take stock on his "starry eyed" view that the private sector could deliver

"Our members are very disappointed that Tony Blair having won such a big mandate at the last election and should have been hitting public service workers in the way he has been.

"It will take a massive effort to get public service workers' morale back on stream."

Confrontation not wanted

Labour Party chairman Charles Clarke denied ministers believed public services could only improve by using private firms.

"What is critically important is we look in a pragmatic way... at what's the best thing for each public service without an ideological, a doctrinal blockage which says either private good, public bad or private bad, public good."

He added: "Neither the government nor Tony Blair are looking for any confrontation with anybody. That has not been the case."

With some predicting a hostile mood, TUC general secretary John Monks said he thought the prime minister would be "respectfully received" at the conference.

"We are better behaved than the Women's Institute," he said, referring to the slow handclap which greeted Mr Blair at last year's WI conference.