The prime minister and other senior ministers have been criticised for backing away from public sector reforms amid heavy political pressure.

A think tank has warned that David Cameron’s support for key changes to the NHS and other services has “drifted”.

As a result ministers such as health secretary Andrew Lansley had been “exposed to attack”.

The report from think tank Reform came with the government still struggling to get its controversial health service shake-up through parliament.

Ministers have already accepted scores of amendments - and could be forced to make further concessions.

The thinktank examined the state of the coalition’s policies to assess the progress being made by departments.

While last year saw “undoubted successes” for the coalition’s agenda, there were also “reverses and retreats on an equally large scale”, it said.

And Mr Cameron’s support for public service reform had weakened since he launched the white paper last year, according to the thinktank.

He had gone from criticising the “old-fashioned, top-down, take-what-you’re-given” approach to public services, to “micromanaging NHS waiting times, nursing standards, adoption and troubled families”.

“The prime minister’s commitment to public service reform has wavered and this leaves his reforming ministers exposed to attack.”

Meanwhile, George Osborne’s Treasury “has been absent from the debate on public service reform when it should have been driving it”.

The report said: “The NHS reversal has overshadowed the whole reform agenda. The government’s new position on the NHS contradicts the key principles in the Open Public Services White Paper.

“As reform has stalled, the service has begun to deteriorate [in terms of longer waiting times and withdrawal of services]… there is no disciplined commitment to the principles of reform.”

The report called for the spending review to be reopened and the protection for health and schools budgets dropped.

The coalition should also push ahead with introducing regionalised pay in the public sector, and review working practices in education and the NHS.

A Department of Health spokeswoman said: “We are getting on with modernising the NHS whilst performance is actually improving.

“Waiting times are low and stable, infections are down and mixed-sex accommodation has plummeted by 94 per cent.

“The Health and Social Care Bill, currently being debated in Parliament, safeguards the future of our NHS, and moves us closer to a health service that puts patients at the heart of everything it does.

“Patients around the country will shortly start to benefit from our plans to increase choice, and clinicians covering 97 per cent of the population are already taking responsibility for delivering better care for their patients.”