MPs have overturned a proposal to make a referendum on the Westminster voting system non-binding unless 40 per cent of the electorate take part in the poll. Peers backed the measure earlier this month but the Commons rejected the proposal by a majority of 70.
Cabinet Office minister Mark Harper said there was a "compelling" case for voters to make the final decision.
MPs rejected a number of other Lords amendments as they sought to pass a bill needed to enable the referendum.
Ministers said that they had listened to concerns from MPs and peers over the bill and "engaged constructively" over the most contentious issues but Labour said the bill was being "bulldozed" through Parliament.
The Parliamentary Voting System and Constituencies Bill has to be approved by Parliament by today so that it can become law in time to hold the referendum on the Westminster voting system on 5 May as intended by the Government.