Rishi Sunak under fire for leaving public in dark about his plans for No 10

Rishi Sunak will become the UK’s third prime minister in just seven weeks in a remarkable comeback, but left the public in the dark about his rescue plan for the economic crisis he inherits.

After seeing off the challenge of Penny Mordaunt, the former chancellor – who made no speeches during the campaign – promised to lead with “integrity and humility”, but spoke for just 83 seconds and took no questions.

Mr Sunak is set to press ahead with next Monday’s de-facto Budget, when huge spending cuts and tax hikes are certain, prompting opposition parties to attack his failure to explain his blueprint for power.

Angela Rayner, Labour’s deputy leader, seized on the brief speech, saying: “With his record – and after Liz Truss comprehensively beat him over the summer – it’s no wonder he is dodging scrutiny.”

And Sarah Olney, the Liberal Democrat Treasury spokesperson, protested: “He said nothing about his plans for the country, leaving the public in the dark while he celebrates behind closed doors with Conservative MPs.”

Underlining the daunting challenges ahead, Mr Sunak faced immediate demands not to impose real-terms benefits cuts, yet also to set out “fully costed plans” to restore economic stability.

He also came under fire for ruling out an early general election, at a private meeting where he warned Tory MPs of “an existential threat” unless the party wins back public trust destroyed by Ms Truss’s disastrous premiership.

Almost 400,000 people have signed The Independent’s campaign petition for an immediate election – a move backed by 63 per cent of the public, a poll last week found.

In an awkward speech at Conservative headquarters, the man set to be Britain’s youngest prime minister for 200 years, at just 42, told his party: “The United Kingdom is a great country, but there is no doubt we face a profound economic challenge.

“We now need stability and unity and I will make it my utmost priority to bring our party and our country together.”

Mr Sunak’s success was hailed as a historic moment as far away as India, with the UK-born son of Hindus of Punjabi-Indian descent poised to become the first non-white prime minister.

It comes just weeks after he was heavily defeated by Ms Truss in the members’ ballot to replace Boris Johnson – when many speculated he would quit politics altogether, his chance gone.

Earlier, Mr Sunak promised his MPs a broad-based cabinet, after Ms Truss had exiled his supporters and paid the price of immediate party revolts over her market-crashing tax cuts.

One former cabinet minister told The Independent: “He should keep in the cabinet people like [Jacob] Rees-Mogg and other Johnson supporters, to show that he is appointing people from all wings of the party. That he is doing the opposite of what Truss did.”

Ms Truss, Theresa May and David Cameron all tweeted their congratulations – but there was no immediate word from Mr Johnson, who pulled out of the contest on Sunday night.

Mr Sunak’s victory was sealed when Mr Mordaunt followed Mr Johnson out of the race, failing to gather the 100 nominations from colleagues required to prolong the fight.

Minutes later, Graham Brady, the chair of the Tory backbench 1922 Committee, formally announced the result, saying: “I can confirm that we have one valid nomination, and Rishi Sunak is elected as leader of the Conservative Party.”

He will meet the King and take over as prime minister on Tuesday – after Ms Truss holds a final cabinet meeting – probably with a speech outside No 10 in the late morning.

One Conservative MP who heard Mr Sunak’s private speech told journalists: “He said we are facing an existential threat – but it is not an existential threat that is inevitable.

“He said we have one shot to get it right, to restore faith and trust in British politics, and there will no second chances.”

The Child Poverty Action Group led calls for Mr Sunak to stick to his promise, made earlier this year, to uprate benefits in line with inflation, not much-lower wages.

“If the pledge isn’t honoured, we won’t be the country the PM wants where the next generation has more than the last, we’ll be a country of soaring child poverty,” said Alison Garnham, its chief executive.

Business groups urged him not to delay next Monday’s “medium-term fiscal plan”, the British Chambers of Commerce saying that “the political and economic uncertainty must now come to an end”.

“This means setting out fully costed plans to deal with the big issues facing businesses; soaring energy bills, labour shortages, spiralling inflation, and climbing interest rates,” said Shevaun Haviland, its director general.

Kierra Box, of Friends of the Earth, cast doubt on Mr Sunak’s commitment to the net zero commitment, saying: “His track record as chancellor – which saw new North Sea oil and gas fast-tracked, levies for domestic flights cut and a weak windfall tax on profiting fossil fuel companies imposed – suggests otherwise.”