Rishi Sunak has refused to offer nurses a better pay rise despite growing pressure from Tory MPs.
Thousands of nurses across the country walked out on Thursday in the dispute over pay and conditions. A further strike is planned for Tuesday.
The Royal College of Nursing (RCN) has demanded a pay rise of around 19% in order to cope with surging inflation. The government has said this is unaffordable and offered around 4%.
Ministers have argued they are simply following the recommendation of the independent NHS Pay Review Body, although critics have pointed out that it has to operate within constraints set by the government.
Speaking in Northern Ireland on Friday, the prime minister told the BBC he was not changing his mind.
“The health secretary has always been clear, the door is always open, that’s always been the case,” he said.
“But we want to be fair, reasonable and constructive, that’s why we accepted the recommendations of an independent pay body about what fair pay would be.”
But Jake Berry, who served as Conservative Party chairman while Liz Truss was PM before being sacked by Sunak, told Times Radio: "It is time for pragmatism and talking between the government and the unions. I don’t see why that is controversial.
“Machismo and sort of chest beating and ‘we’ll take the unions on’ doesn’t work. You only get these things sorted out by talking.”
Tory MP Dan Poulter, a doctor who has also been a health minister, told The Guardian that the government should “improve on the current offer on the table”.
Jerry Cope, a former head of the pay review body, said it should be asked to look at the offer again.
He told BBC Radio 4′s Today programme the “world was a rather different place” when they made their considerations and was now “probably out of date”.
Steve Brine, the Conservative chairman of the Commons health committee, also said this was a “sensible answer” to the impasse.
A YouGov poll of more than 5,000 adults from across Britain found that 64% supported strikes while 28% opposed them.
