David Cameron has staked the Tories' claim to be the party of the NHS, pledging to end the targets he says are destroying the service.
He said government targets had turned the NHS into a "vast inhuman machine" and that only the Tories could restore staff morale and improve patient care.
The Tory leader also accused Gordon Brown - Tony Blair's likely successor - of being obsessed with spin.
Labour called his NHS claims "absurd" and said no-one would believe them.
The Liberal Democrats accused both parties of "cynically turning the NHS into a political football".
In his boldest move yet on to traditional Labour territory, Mr Cameron used his closing speech at his party's spring conference to project the Conservatives as the party of the public services.
The Tory leader also hit back at criticism his environmental policies lacked substance, arguing his proposal to tax aviation proved he meant business - although he stressed they would be offset by tax cuts elsewhere.
"Anyone can say they're green. It's easy to do the softer things like ride your bike, visit glaciers and rebuild your house to make it green," he told delegates.
But he added: "It's only clear you mean it when you do the tough things as well."
On the NHS, he told delegates: "It used to be said that Labour were the party of the NHS - not any more.
"The NHS is my passion, our priority - we'll back it, build it and improve it for everyone. That is my pledge today."
He said it was not that Labour did not care about the NHS, but that their "values and philosophy" were undermining it.
"Labour's mania for controlling and directing things from the centre.
"Labour's pessimism about human nature, Labour's belief that if people aren't told what to do, they'll do the wrong thing. Labour just don't trust people."
'Heart and soul'
Mr Cameron said Labour has turned the NHS into a "vast, inhuman machine, a pen-pushers' paradise at the mercy of the management consultants' latest wheeze".
And he insisted "today's Conservative Party backs the NHS, heart and soul".
He said the Tories would scrap targets and "pointless reorganisations" and "put people back at the heart of the NHS".
Senior Tories have been in an optimistic mood during the Nottingham conference and they were given a further boost by a YouGov poll in the Sunday Times, which suggested the party had increased its lead over Labour to 6%.
Shadow chancellor, George Osborne told BBC One's Sunday AM: "I think we now look like the alternative government."
Former leader William Hague told delegates on Saturday: "In the last 15 months no-one can doubt any longer that the Conservative Party has begun its journey back to power.
"We have set the pace, made the news, won elections and topped the polls, and after a decade-and-a-half in the doldrums that feels good."
But Labour will not give up its traditional role as the party of the NHS without a fight - and they claim voters will not believe Tory promises on health.
"The more David Cameron and the Conservatives talk about the NHS the more they are going to be found out," Health Secretary Patricia Hewitt told ITV's Sunday Edition.
She said Mr Cameron's accusations were "absurd" and the Conservatives had voted against reforms and their spending plans would mean annual cuts of £28bn in services.