A prolonged NHS crisis stoked by further strikes risks derailing Rishi Sunak’s local election plans amid Tory concern that the prime minister is already facing pressure over pledges on health and the economy. The prime minister will head to the south-east this week as he attempts to shore up Tory heartland seats where traditional supporters had been put off by the chaos of the Johnson and Truss regimes. However, opposition parties have reported findings that the NHS remains the most salient issue among soft Tory voters. The decision by the Royal College of Nursing (RCN) to reject the government’s pay offer and announce further strike action, together with the threat of coordinated strikes by junior doctors, has heaped new pressure on Sunak’s pledge to reduce waiting lists by the end of the year. It has also handed Labour and the Lib Dems a boost ahead of a huge set of local elections in England that represents Sunak’s first electoral test since entering Downing Street. “The RCN rejecting the nursing pay deal and the likelihood of further junior doctor strikes is bad news for the government, which had been making good progress in restoring a semblance of order after the chaos of the Johnson and Truss regimes,” said a former Tory minister. “There is a political imperative to put the strikes in the rear-view mirror.” Speaking on Sunday morning, the Conservative party chair, Greg Hands, said the party expected to lose more than 1,000 seats in the local elections on 4 May. This would be a notably poor result for the Tories given that they lost more than 1,300 councillors the last time the seats were fought, in 2019, amid the trough of Theresa May’s electoral unpopularity. “The independent expectations are that the Conservatives will lose more than 1,000 seats and that Labour need to make big gains,” Hands told Sky’s Sophy Ridge on Sunday programme. Asked if this was expectation management, Hands said it was “independent predictions from the most credible academic sources”. According to an Opinium poll earlier this year, the most important of Sunak’s “five priorities” to the public is cutting NHS waiting lists. Cutting national debt is more of a “nice-to-have”, while 25% said new laws on small boats crossing the Channel were not a priority. Campaigners in the so-called blue wall seats – where affluent, liberal Tory voters have been drifting away from the party – have already reported their surprise at finding that the NHS has emerged as the main concern on the doorstep rather than more familiar issues in the seats, such as tax cuts. “The NHS is the most salient issue on the doorstep for 2019 Tory voters, and now their failure to manage it will be on the front of newspapers day in, day out,” said a senior Lib Dem source. “My personal view is that the reason they keep going for immigration/asylum seekers is that they basically think anything is better than the story being the NHS.” It comes at a time when most Tory MPs have been pleasantly surprised by the progress Sunak has made since becoming prime minister, which has seen him adopt cutting NHS waiting times as one of his five “priorities for 2023”. Yet the vague NHS pledge is suddenly looking harder to achieve than was initially believed. Sunak’s team is acutely aware of the importance of improving the NHS over this year. James Forsyth, his political secretary, has long believed that a prolonged NHS crisis is likely to be a greater problem for the hopes of the party than high energy bills and the cost of living. Some senior Tories are hoping that public support for nurses will turn as the strikes continue. “I am not sure that public sympathy will continue as a reasonable package for nurses was rejected,” said one former cabinet minister. “People are starting to realise that strikes inhibit economic growth, too. I think that the PM’s pledges look much more ambitious than perhaps was realised earlier this year, but that is a good thing.” While the target of cutting waiting times is vague, the events of the last week have made the task far harder, according to senior NHS figures. “We cannot overlook the consequences of this week’s strike action,” said Matthew Taylor, chief executive of the NHS Confederation, pointing to the number of outpatient appointments and operations rescheduled, estimated at between 250,000 and 330,000. “A huge amount of effort has gone into cancelling and then finding new dates for these appointments. With a waiting list already over the 7m mark and an understaffed workforce, these extra cancellations will only further delay progress in getting the waiting list down. Longer term, many are mindful about how they will recover lost ground when it comes to the backlog, and they are always concerned for the health of patients who have had operations and appointments pushed back.” It is not the only one of Sunak’s five pledges to be under pressure this spring, despite the fact that the list was seen as easy for the government to achieve. Recent economic data has also put pressure on the promise to get “national debt falling”. Carl Emmerson, deputy director of the Institute for Fiscal Studies, said the chancellor, Jeremy Hunt, was only just meeting his very loose fiscal targets. “What’s notable about the current target, to have debt falling in five years’ time, is just how loose it is compared with previous targets,” he said, “and that, despite this, the government is still only meeting it by a hair’s breadth.”