Sir Keir Starmer is to set out an “unrelenting” approach to ensuring the public feel the benefits or economic growth and improved public services, No 10 said.

The Prime Minister will deliver a major speech on Thursday following a backlash to the Budget, plummeting poll ratings and the first resignation from his Cabinet.

Ministers and officials have insisted the “Plan for Change” is not a reset after just five months in office but an attempt to show how the Government will deliver on the five “missions” set out in the Labour manifesto.

“We’ve been clear that this marks the next phase of our mission-led Government,” the Prime Minister’s official spokesman said.

Recent weeks have seen farmers and business chiefs criticise the Budget’s tax rises and Louise Haigh forced to quit as transport secretary over a fraud offence before she became an MP.

Downing Street insisted the Government remains committed to its top priority of achieving the fastest economic growth in the G7 group of wealthy democracies – the UK, US, Canada, Japan, France, Italy and Germany – despite a Telegraph report that the pledge had been sidelined.

But No 10 said the “milestones” set out by Sir Keir on Thursday will be about ensuring people feel the benefit of economic growth, rather than the overall percentage increase in gross domestic product.

The Prime Minister’s official spokesman said: “We’ve always been clear that the benefits of growth must be felt by working people, and the milestones set out later in the week will set out how we’re going to achieve that.”

Along with economic growth, Labour’s other missions involve making the UK a clean energy “superpower”, halving serious violent crime as part of a plan to “take back our streets”, reforming childcare and education to break down barriers to opportunity, and building an NHS fit for the future.

Downing Street insisted the targets being set for the NHS will be ambitious but achievable.

Sir Keir will promise that by March 2029 the NHS will meet its target of carrying out 92% of routine operations and appointments within 18 weeks, a target that has not been achieved for almost a decade, The Times reported.

The Prime Minister’s official spokesman said: “What you are seeing with all these milestones is that they are going to be ambitious – there’s no point in setting milestones that aren’t ambitious – but we do think that they are achievable.

“When it comes to the NHS, as the Darzi Review showed, we inherited an NHS that’s broken and the manifesto showed clearly that tackling waiting lists would be our immediate priority.”

The Times carried warnings from an NHS source that the focus on meeting the 18-week target could have knock-on effects elsewhere in England’s health service, leading to “warzone A&E departments and all sorts of other things being sidelined” such as mental health and community care.

Asked about the concerns, the spokesman said: “Tackling waiting lists is a critical step in taking pressures off A&E, off GP services, it’s why it’s been set out as one of the Government’s priority aims in office.

“That’s not to say that the Government isn’t going to continue to take action on wider priorities in the NHS.

“We’ve already resolved A&E strikes, making this the first winter in three years that all A&E staff will be on the front line rather than the picket line.”

The spokesman said the “Plan for Change” will require “relentless focus” and “prioritisation in order to deliver for working people”.

“It will be accompanied by a clear message from the PM that we continue to take an unrelenting approach to deliver on the priorities of working people,” he added.

Downing Street later indicated immigration would also feature in the Prime Minister’s speech, and said Sir Keir had made clear his wish to “significantly reduce net migration”.