Politicians must have the guts to back the huge changes the National Health Service needs to make in order to come up with £20 billion of savings over four years.

That was one of the key messages delivered by Sir David Nicholson, the NHS chief executive, speaking at the NHS Confederation conference in Manchester. He called on MPs from all parties to acknowledge to the public the fact that "some parts of the NHS will not do everything in the future" and back unpopular moves such as hospital closures.

He added that "we can't have a series of witch hunts. Politicians need to back us", though he believes the support is there at present. Sir David said that MPs from both the government and the opposition have given "a ringing endorsement" to the service and he praised Prime Minister David Cameron in particular for "nailing his colours to the mast" in supporting  a tax-funded public health service.

Sir David also feels that the concerns regularly aired during the conference about lack of support for NHS chiefs from Westminster may soon be eased. "When politicians come in, they don't 'get' management", he said, but he is convinced this government does indeed 'get' it.

He went on to say that the NHS has come up with an "absolutely remarkable set of results" in the last year, especially against the background of doom and gloom reported in the media and by bloggers. The service has delivered or improved on many of its targets but "I still don't think it is enough".

Sir David reiterated previous calls for more localised services and said that while GPs will be at the heart of clinical commissioning, due to their "unique position" in the community, they will need help from specialists, nurses and so on.

In an amusing footnote, at the end of his speech, Sir David was asked by Sarah Montague (of BBC's Today programme and moderator) about his Stalinesque reputation. As delegates flooded out of the auditorium before he started his reply, he quipped: "I bet people wouldn't be going out if Stalin was speaking".