Theresa May's Conservatives have confirmed widely expected plans for a new cap on energy prices in the party's election platform.
Details on the exact measure remain scarce, but Downing Street is known to have held talks with former minister John Penrose over his proposal for a "relative price cap".
Penrose's proposals would limit the maximum increases for customers on default tariffs, and are understood to be one of the options under consideration by ministers.
However, the intervention has already proved controversial, with voices including British Gas owner Centrica warning that the approach risks hitting competition in the sector.
Proposals are likely to be unveiled by May's Conservatives in a manifesto launch expected to take place next week.
Labour will unveil its own manifesto on 15 May.