Tony Blair warned Midland MPs last night there would be no compromise with his opponents within the Labour movement, at the start of Labour's annual conference in Brighton.
At a reception for the region's MPs he said: "Resisting change will only let the country down and lead to a more unfair and unjust society."
The conference is set to debate union demands for a change in the law to allow secondary picketing during strikes, and calls for an end to the involvement of the private sector in delivering health services. But the Prime Minister made it clear there would be no U-turn on public service reform.
Highlighting the slogan of the conference, Securing Britain's Future, he said: "My recent visits to China and India have brought home even further the magnitude of the global challenge we face.
"We have to change and modernise for a purpose - to equip everyone for the changing world."
The slogan is also being seen as a reference to Mr Blair's desire to ensure his own party's future is secure once he stands down as leader.
Mr Blair said: "Faced with the opportunities and insecurities the future brings, our New Labour Government must manage this change and not turn our face against it."
In recent conferences, unions have inflicted a series of defeats on the Labour leadership.
Senior figures within the party were privately admitting yesterday that a similar defeat on an issue such as NHS reform was possible this year. However, they expect to win the vote among party members, even if the union block vote goes against them.
The UNISON resolution attacks the use of private finance for hospitals and the creation of Foundation Hospitals, such as the new Queen Elizabeth Hospital in Edgbaston.