Prime Minister Tony Blair has arrived for Labour's annual conference, bringing the message that there should be further reform of public services.
Tony Blair was applauded as he arrived in Brighton
Mr Blair, in his last term as prime minister, wants to focus on what is needed to win a fourth term in power.
However, he faces a growing campaign against more private sector involvement in the health service.
During the week he faces challenges over the war in Iraq, from unions, and from women's and pensioners' groups.
Writing in the conference guide, Mr Blair said Labour's "record of achievement in some areas solid, in others spectacular" had been key in winning a third term.
However, public sector reform must be accelerated if a fourth term was to be won, he says.
"Just as the public wants us to do more to tackle world poverty and climate change, so they want us to step up the pace of reform at home," he writes.
Health service debate
Former health secretary Frank Dobson is among signatories to a letter in the Guardian newspaper, arguing against what they see as the stealthy privatisation of the NHS.
"At the heart of the changes is the creation of a market that welcomes profit-driven international corporations and will compel hospitals and health professionals to compete with each other," they write.
But health secretary Patricia Hewitt said "reforms are benefiting patients" and that "independent providers have led to greater efficiency".
Police are out in force to ensure the safety of delegates and MPs
"We are not turning the NHS into a private service and we will never abandon the principle that healthcare should be free at the point of need, not based on the ability to pay," she said.
Mr Blair appears determined to use the conference to call for reforms in industry, health, education and welfare.
He said helping Britain meet the challenges of the new global economy would be the central message of the conference, whose theme is "Securing Britain's Future".
He wants to highlight the changing global economy and the increasing power of China and India.
He has also stressed the need to push on with reforming the public sector.
Unions are not only unhappy about greater use of private firms in the NHS, they are also concerned about public sector pension reforms, including a possible raising of the retirement age.
The conference - which starts on Sunday - will see union leaders call for a rethink of employment laws.
But political correspondents said Iraq could still be the most contentious issue in Brighton.
The question of who will be the next party leader will also be a major topic, correspondents say.
Security services and armed police were patrolling the streets of Brighton ahead of the conference opening on Sunday.
More than 1,300 police officers are taking part in the £3.7m security operation, dubbed Otter, in the city.