Theresa May will press ahead today with a promise to cap energy prices for 17 million households despite warnings that the move could force up bills for other customers.
The Conservative general election manifesto will include a pledge to regulate the maximum costs of standard variable tariffs, the default deals for the two thirds of customers who have not sought cheaper alternatives. The prime minister said that she expected the price cap to save families on poor-value tariffs as much as £100 a year.
Introducing a cash limit is the most radical of options that had been under consideration by the government. It is arguably the most significant intervention in the market since privatisation.
Energy companies, which are lobbying against a cap, have claimed that the move would kill competition, deter investment and endanger jobs. They are expected to try to protect their profits by scrapping cut-price deals, which can be hundreds of pounds a year cheaper, so forcing up bills for savvy customers.
Senior Conservatives, including Lord Lawson of Blaby, the former chancellor, have voiced their opposition, with some in government privately pressing for watered-down reforms.