Nick Clegg has said the government's plans for constitutional change would restore faith in the way MPs were elected.
The deputy prime minister said that while there were differences in the coalition about plans for AV, "where we emphatically agree is that the final decision should be taken not by us but by the British people".
And he said that he knew there were "different views" in the coalition over plans to hold a referendum to change the Westminster voting rules on the same day as elections in Scotland, Wales and Northern Ireland.
He said: "Parliamentary elections are the foundation of our democracy, it is vital to our political system as a whole that they are considered to be legitimate and fair that is what this bill is seeking to deliver."
MPs were debating the Parliamentary Voting and Constituencies Bill on 6 September 2010.
The bill paves the way for a referendum on changing the Westminster electoral system from first-past-the-post to the Alternative Vote (AV) system, whereby voters rank candidates in order of preference on the ballot paper.
The referendum was paramount to a coalition deal being agreed between the Conservatives and Lib Dems following the May general election.
The Tories are opposed to changing the electoral system, and a total of 43 MPs have signed a Commons motion calling for the date of the referendum to be changed, fearing it will lead to different levels of turnout.
The bill also proposes cutting the number of MPs by 50, to 600, and redrawing parliamentary boundaries to make constituencies more equal in size.
Labour has tabled a reasoned amendment opposing the bill as a whole arguing that electoral reform, which it supports, should not be tied up with "hasty" boundary changes in one piece of legislation.
Shadow justice secretary Jack Straw challenged the timing of the plebiscite, claiming the chances of a yes vote will be diminished by the "deep unpopularity" of the government by May.
He condemned the changes to the number and size of parliamentary constituencies as the "worst kind of political skulduggery for narrow party advantage".
He said that the plan for boundary changes was "one of the most partisan proposals we have seen in recent years".
Watch the second part of the debate