Ed Miliband's proposal to freeze energy prices for 20 months if Labour are elected in 2015, will "hurt people", the Energy Secretary told Daybreak.
The energy companies would "push up bills before Miliband's freeze and afterwards", Ed Davey said.
In turn, he claimed, this would "hurt" the fuel poor and "undermine" investment in green energies.
The coalition has unveiled measures it says will knock £50 off the average energy bill, but some of that cost will be absorbed by taxpayers.
The Government has laid out its ideas on how to cut energy bills this winter - but the plan has been put together in haste.