Money Saving Expert Martin Lewis has said there is "nothing stopping" the government from acting now to protect households from "cataclysmic" increases to their energy bills.
Lewis warned millions across Britain are facing a "a financial emergency that risks lives" as energy bills skyrocket in the coming months amid the ongoing cost of living crisis.
New forecasts suggest regulator Ofgem will hike the price cap on energy bills to £3,582 per year for the average household in Great Britain from the beginning of October.
Analysts at Cornwall Insight predict further rises, with bills rising to £4,266 in January and then to £4,427 from the start of April.
Lewis has accused the government of failing to act ahead of time.
"We know this is coming," Lewis told BBC Radio 4's Today Programme.
"Frankly we know almost exactly what's going to happen. We know that the price cap rises I'm talking about are accurate."
He added: "Ultimately it is government and government alone which is the only one which can stop the terrible, cataclysmic risk millions of people in our nation face this winter."
The price cap - which decides a limit on the maximum amount suppliers can charge for each unit of gas and electricity you use - is set by a methodology published by regulator Ofgem.
It originally changed every six months, but is now reviewed every three months.
Ofgem says this is part of an effort to enable prices to go down quickly. However, instead the change has allowed prices to increase more frequently.
Watch: Martin Lewis warns of ‘catastrophe’ over soaring energy bills
Tory leadership candidates Liz Truss and Rishi Sunak are facing renewed pressure to outline specific plans to tackle to spiralling cost of living crisis.
Lewis has said it is "complete bull" that the candidates haven't been entirely clear how they will handle the crisis.
Education secretary James Cleverly told ITV’s Good Morning Britain that “the candidates cannot put their plans into practice until they are prime minister”.
But hitting back, Lewis said: “What a load of bull. That is complete bull.
"I won’t use the final word on the back of it. That’s just simply not true.”
Derek Lickorish, chairman of energy firm Utilita and former chair of the Committee on Fuel Poverty, called for “unity of purpose” between Boris Johnson and the two prime ministerial candidates to tackle the threat to the poorest people posed by rising energy costs.
Speaking to BBC Radio 4’s Today Programme, he said: “The situation is absolutely dire and I am astonished that we don’t see the two political contenders for prime minister declare a unity of purpose over this issue, along with the current prime minister, and start sorting it out.
“We have to do something very profound, we have to do it quickly because all the time we’re sitting here the clock is ticking and the price of gas keeps on increasing.”
Former chancellor Sunak has said he has “no doubt” extra support will be needed to get people through the winter, and he is “confident” he can find the money needed to ease the burden from government efficiency savings.
Speaking during a campaign visit to Huddersfield, the foreign secretary said that if she became prime minister she would “see what the situation is like” in the autumn.
Her refusal to commit to extra support has sparked widespread criticism, with Lewis branding her plans to cut the green levy on energy bills a "sticking plaster over a gaping wound".
Deputy prime minister Dominic Raab - who is backing Sunak - called her tax cutting approach an "electoral suicide note" in a newspaper column this week, warning that it could prove “economically harmful and politically fatal” for the Conservatives.