Prime Minister Tony Blair has defended change in the NHS, and predicted it will lead to better patient care.
In a speech to the NHS Confederation, he called on managers and doctors to sell reforms to the public in England.
Mr Blair said many people were resistant to change, but it was necessary to improve patient services.
It comes as a left-wing think tank warns campaigns to save local A&E units from closure could lead to more than 1,000 unnecessary deaths each year.
The Institute for Public Policy Research (IPPR) said specialist units were better for high-risk patients.
Critics of the reforms say downgrading traditional A&E units will put patient lives at risk and are being carried out to cut costs.
And the Guardian newspaper reports that ministers have accepted in private that they have failed to sell NHS reform effectively to the public.
Speaking to an audience of NHS managers and doctors, Mr Blair said service improvements in NHS hospitals were being implemented to ensure the very sick have speedy access to specialist care but also to treat people more conveniently closer to home.
The Prime Minister said no change was not an option. The key was to shape change to ensure a vibrant future for the NHS.
He conceded that there was "in-built resistance" to change, and that managers had a tough job selling it to the public.
But he said: "The best reason for all this change is the best reason there possibly can be: better care for the patient.
"I genuinely believe the best is yet to come with more lives saved, stopping more pain and distress."
Range of reforms
Meanwhile, two government advisers, Sir George Alberti and Professor Roger Boyle, have published separate reports arguing the case for reform of services.
They set out a pyramid structure whereby super regional hospitals and specialist centres would provide the most complex care, while the second tier includes local hospitals with minor injury units - a scaled down version of A&E - walk-in centres and specialist GP services.
There will also be more of an emphasis on providing care at home and in community settings.
Professor Boyle, the national director for coronary heart disease, told the BBC: "The message is quite a simple one. Modern medicine moves on, the new technologies need to be made available to everybody, they do require more specialised care, and they require more specialised investigation.
"We have to move the patients to the expertise rather more than we do at the moment."
The IPPR finding is based on data showing how many extra lives could be saved if everyone had access to new techniques to treat heart attacks.
If heart attack care was reconfigured to ensure universal access to emergency angioplasty, around 500 extra lives could be saved every year, it said.
Last year only 1,600 of 61,000 heart attack patients were treated in a specialist unit.
Also there is evidence that people who have suffered severe injury are more likely to survive if they are treated in specialist centres rather than local hospitals.
The Royal College of Surgeons and British Orthopaedic Society estimates that universal access to specialist trauma centres could save around 770 lives a year.
The IPPR researchers said people should be out on the streets campaigning for changes to the way hospitals provide services rather than campaigning to keep traditional services open.
"We're not saying that hospitals should close, we're talking about reconfiguring services," said IPPR research fellow Joe Farrington-Douglas.
He said: "The NHS and government should be able to demonstrate how changes will improve care and local people should hold the NHS to account, but they need to understand that preserving the local hospital will not always be in their best interest if something life-threatening happens."
He added: "Some district hospitals are not as safe as they should be and that point has not been effectively made."
Dr Jonathan Fielden, chairman of the BMA's consultants' committee said decisions on reconfiguration must be based on "good evidence".
"It is absolutely right that there is a public debate about the way our health services are delivered in the future and it is vital that patients and clinicians are properly informed and engaged in these discussions," he said.
Professor Christopher Marks, cancer surgeon and chairman of the independent campaign to save the Royal Surrey Hospital in Guildford, said: "What local people want is access to excellent care which they can get to easily."
He accepted that some complicated cases must go to specialist centres, but warned centralisation of services in Surrey would see a doubling of minimum ambulance times, which could compromise care.
"Thanks to the money that the government has put in, particularly to A&E, the service has improved marvellously, and it is a pity to throw the baby out with the bath water when you have spent all this money."
Dr Richard Taylor, the independent MP for Wyre Forest, who campaigned against the closure of his local hospital in Kidderminster, admitted that campaigns to save local facilities were driven in some part by emotion.
But he warned that downgrading A&E units left them unable to cope.
"There has got to be compromise that keeps adequate facilities at a wider range of acute general hospitals than these super-specialist centres alone."