The political parties are preparing to negotiate their position in a hung parliament which looks set to be dominated by the Conservatives.
Cabinet Minister Lord Mandelson told the Today programme that the election results demonstrated that "the public don't want any single party to have a monopoly of power and we have got to respond to that with electoral reform."
He explained that the Liberal Democrats, "will only advance their most important priority of the electoral reform through the Labour party and not the Tory party," in forming a potential coalition.
The first past the post system "is creaking at the seams," he said, "given all that has happened over the past 18 months the public is now up for change."
Lord Mandelson clarified that Gordon Brown is "not a block" to change of electoral reform: "he has learnt some lessons of what's happened and like many of us believes that public wants change."
Shadow cabinet minister Theresa May rejected suggestions that "this was a vote for electoral reform".
"I find it slightly strange at time when we're facing such severe economic problems in this country that the one issue that seems to be key to the Liberal Democrats is electoral reform," she told Today presenter John Humphrys.
"Lord Mandelson now seems to be putting as somewhat as you say of a deathbed conversion for the Labour party, now putting such high relevance to the issue of electoral reform".
She reiterated that "Labour has lost the election, they have rejected the Labour party. This is an historic result for the Conservatives."
When asked again about whether her party will put forward a referendum for electoral reform, she explained that the party "would not cling onto power for the sake of power, we will do what is in the national interest."
Get in touch with Today via
or text us on 84844.