Labour have surged to a 33-point lead over the Tories, the largest lead any party has enjoyed since the late 1990s, according to new polling.
On the eve of the Tory conference, a poll by YouGov, carried out on Wednesday and Thursday, put Labour on 54% compared to the Conservatives’ 21%.
If the results were replicated in a general election, Labour would win 498 seats - a gain of 296.
The Tories, meanwhile, would slide to just 61 seats, giving Labour a majority of 346 and virtually wiping out the Conservatives who currently hold 365 seats.
Conservative MP Sir Charles Walker admitted that his party would likely lose an election if it was called today based on the polling, but ruled out the possibility of a leadership challenge against Ms Truss. “We’ve made our bed, we’ve got to lie in it,” he said.
The results come amid market turmoil and public outcry following last Friday’s mini-budget.
Sir Keir Starmer told ITV News on Wednesday, his "hope" of gaining the keys to Number 10 had turned into "belief" following the party conference.
"We've done a huge amount of work to change the Labour party over the last two years," he said.
"And the polls are reflecting that, the confidence is reflecting that.
"I know we've got to earn every vote but nobody is now saying to me it's impossible for Labour to win the next election.
"In fact, a hope of winning has turned into a belief that we will win."
Sir Keir called for Parliament to be recalled and the mini-budget reversed after Chancellor Kwasi Kwarteng was accused of delivering a mini-budget that delivered only for high-earners last Friday and heaped costs onto ordinary people.
Ms Truss and Ms Kwarteng have insisted their £45 billion package of tax cuts is the “right plan” to get the economy moving despite chaos on the financial markets and fears of rocketing mortgage bills.
However, Labour warned that households would pay the price with thousands of pounds added to mortgage bills as the Bank of England will be forced to increase interest rates to shore up the pound.
Amid the economic turmoil unleashed by last week's announcement, the Bank of England said it was stepping in to buy up to £65 billion worth of government bonds – known as gilts – at an “urgent pace” after fears over the government’s tax-cutting plans sent the pound tumbling and sparked a sell-off in the gilts market, which left some UK pension funds teetering on the brink of collapse.
Labour are also benefitting from a post-conference bounce, with Sir Keir announcing that a government under him would create a publicly-owned, green energy company to cut bills in his keynote speech on Tuesday.
Buoyed with confidence after his party surged ahead of the Conservatives in the polls, the leader set out his vision for the country to great applause as he told the hall to never "forgive" the Tories for "losing control of the economy".
A survey by Ipsos of 1,000 adults after Mr Kwarteng’s announcement on Friday, but before Sir Keir’s conference speech, found 40% trusted Labour “a great deal” or a “fair amount” on the economy overall.
The chancellor previously said he would deliver his medium-term fiscal plan explaining how he would get debt falling as a percentage of GDP, alongside the updated OBR forecasts, on November 23. But with the absence of any forecasts to accompany Friday’s “fiscal event” seen as a key factor in spooking the markets, many Tory MPs believe that is too long to wait if they are to restore stability.
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Mel Stride, the Conservative chairman of the Commons Treasury Committee, said it should be brought forward to late October – or even earlier – as there was an “urgent need” to increase the confidence of the markets. Mr Kwarteng brushed off suggestions his mini-budget had been a “major economic disaster”, saying: “Without growth you are not going to get the public services, we are not going to generate the income and the tax revenue to pay for public services. “That’s why the mini-budget was absolutely essential in re-setting the debate around growth and focusing us on delivering much better outcomes for our people.” The Prime Minister told BBC Radio Leeds: “We had to take urgent action to get our economy growing, get Britain moving and also deal with inflation. “Of course that means taking controversial and difficult decisions but I am prepared to do that.”