Britain has experienced a surge in optimism since the general election, with more people now upbeat about the country’s future than pessimistic, in a sign that Keir Starmer is enjoying a honeymoon period after Labour’s landslide victory.

There has been a 14-point rise in those feeling upbeat since the election took place. Polling by the Public First consultancy found that only 31% of voters were optimistic about the country heading into the election, with 43% pessimistic. In the wake of the election, sentiment had flipped – with 45% optimistic about the country and 30% pessimistic.

It has coincided with a large increase in Starmer’s personal ratings. The latest Opinium poll for the Observer shows a 20-point rise in his net approval rating – the difference between the proportion of people who think he is doing well or badly. His rating has increased from -1% to 19%.

Senior Labour figures believe that there is an atmosphere of relief among the public after the election result, following years of Conservative infighting. They also hope for an international dividend among European leaders as a consequence of a stable government.

However, figures close to Starmer are also acutely aware that the honeymoon could be short-lived. The first parliamentary skirmishes over social care and welfare will begin this week, while the chancellor Rachel Reeves is also facing an immediate dilemma over the new pay deal for NHS workers and teachers.

“We always thought that if we won the election, the emotion in the country would be relief and if the Tories won the election, the emotion in the country would have been despair,” said one. “I think that is the country’s emotion now. I think the relief has been reinforced by the way Keir’s started the job – just seeing a serious person go about it.

“But there’s another side of this. Having a big majority doesn’t change the economic inheritance. People are encouraged to make change, but to do it in the spirit in which we fought and won the election – which was to be quite candid with the electorate about the inheritance we have and what was possible in terms of public spending.”

The boost in optimism appears to reflect an expectation of greater competence, rather than any anticipated major reforms early in Starmer’s tenure. Shortly before the election, half of voters expected him to scrap the Rwanda deportation scheme in the first three to six months, according to the Public First research. Half also believed he would raise the taxes that Labour had committed to increasing, such as VAT on private school fees and an expansion of the levy on oil and gas companies.

Other than those two areas, there were no other policies that the majority of the population expected Starmer to enact within his first six months in power. However, 30% did expect Starmer to substantially increase NHS funding, with the health service one of the major issues he faces amid growing clamour for public sector investment.

Starmer’s first tests will come this week, when Labour rebels will table a vote on abolishing the two-child benefit limit. The issue has become the first major demand of many Labour MPs. Rebels said they were planning continued action inside and outside parliament between now and the first Labour budget expected in October.

Meanwhile the newly emboldened Lib Dems will hold a vote on starting cross-party talks on adult social care. The health secretary Wes Streeting has recently suggested he supports such an approach to fix the issue. Ed Davey, the Lib Dem leader, said solving social care was “essential if we are to give people the care and dignity they deserve and tackle the crisis facing the NHS”.

The most pressing issue is now public sector pay, amid reports that independent pay review bodies are recommending 5.5% pay increases for teachers and NHS workers – far higher than anticipated. It leaves Reeves searching for a compromise that will avoid either damaging her all-important commitment to fiscal discipline or risking a new wave of industrial action.

Denise Baron, associate director at Public First, said the boost in optimism was bigger than she had anticipated, given the backdrop of political cynicism. “Sustaining this optimism will obviously be challenging,” she said. “Implementing major policy changes takes time, and it takes even longer for the public to feel the impact of those decisions. But perhaps the greater hurdle is the sense of cynicism, disillusionment, and even powerlessness that many people have felt in recent years. While the cloud of pessimism has lifted for many and this goodwill lasts, it’s the ideal moment to make some fairly big moves, like his early decision to scrap the Rwanda scheme.”

James Crouch, of Opinium, said: “Elections often result in a honeymoon period for the winning party and their leaders, and this time is no different with Starmer’s approval ratings surging since he became prime minister. This mirrors the surge we saw with Boris Johnson’s ratings when his party won the 2019 general election.”