The prime minister David Cameron has defended the “tough” decisions being made on health and welfare, telling party activists that “fortune favours brave governments”.

Addressing Conservative members at a private event in London, the PM insisted he did not care about “taking a hit” on the controversial NHS reforms because they were “unavoidable and urgent”.

But he sought to reassure the grassroots over the crucial doorstep election issue after months of negative publicity, claiming the health service was “in the party’s DNA and that’s not going to change”.

He argued it was right to push through potentially unpopular measures in a range of areas for the good of the country, including agreeing to go ahead with plans for a high-speed rail link between London and the North that will carve up key Tory heartlands.

But that prompted one party member to cry out ‘No’.

“Oh, yes it is,” Mr Cameron replied.

Deputy prime minister Nick Clegg struck a similar tone as he addressed his party in Cardiff at the Welsh Liberal Democrats’ Spring Conference.

He called on members to have “courage”, insisting “difficult” decisions were being made in the “national interest”.

Mr Cameron went on to tell Tory activists that the government was making cuts because the party “cares” about the country.

It is only by taking “tough and bold action” that the UK will be “stronger and fairer”, not by “playing it safe”, he said.

“People say Conservatives in government are taking tough action because they don’t care,” he said. “But the opposite is true. We’re taking those decisions because we do care.”

Government is not reforming the NHS “because it’s easy, let alone popular” but because it is “right”, the forum heard.

Opponents of the Health and Social Care Bill claim it will lead to backdoor privatisation.

But the NHS will remain “truly there for all”, Mr Cameron insisted. “If we don’t get the NHS right today then it will not cope under all that weight in the years to come.”

The NHS is “an invisible crisis” that would be easy to ignore, he said.

“Sooner or later the cracks would have started to show,” he added. “Queues would have grown. Patients would have been let down.

“So frankly I don’t care about taking a hit. I care that it works to avert that crisis, to make the NHS strong enough for the future.

“That’s why we’re making, what at heart, are some pretty simple changes.”