Labour leadership contenders have been urged to overhaul Britain’s “decaying” electoral system and commit to introducing proportional representation at national elections.

In a letter to those vying to replace Jeremy Corbyn, the Liberal Democrats claim electoral reform has been “dangerously absent” from the party’s leadership contest – now around halfway through.

So far, the three remaining candidates – Lisa Nandy, Rebecca Long-Bailey and Sir Keir Starmer – have not spoken in favour of ditching the current first-past-the-post voting system.

In the wake of Labour’s worst electoral defeat since 1935, however, a poll of Labour members found that three-quarters (76 per cent) supported adopting proportional representation as a policy, with just 12 per cent opposed.

Clive Lewis, who dropped out of the leadership race, said last month the party must embrace a new voting system, as he claimed a commitment to electoral reform was now the “litmus test of Labour’s survival”.

The battle to replace Jeremy Corbyn as Labour leader Show all 8 1 /8 The battle to replace Jeremy Corbyn as Labour leader The battle to replace Jeremy Corbyn as Labour leader Keir Starmer The former director of public prosecutions undoubtedly has announced that he is standing for the leadership. He is highly-regarded by both left-wingers and centrists in the party. As Labour’s shadow Brexit secretary, he played a key role in the party’s eventual backing of a second referendum. Before becoming an MP, he was a human rights lawyer - conducting cases in international courts including the European Court of Human Rights. Launching his bid, Starmer said that Labour must listen to the public on how to change "restore trust in our party as a force for good." A YouGov poll places him comfortably in the lead as the preferred candidate of 36% of party members EPA The battle to replace Jeremy Corbyn as Labour leader Lisa Nandy Wigan MP Lisa Nandy has announced she wil stand for the leadership. In a letter to the Wigan Post she said she wanted to bring Labour "home" to voters in its traditional strongholds who have abandoned the party. Nandy went on to say that she understands "that we have one chance to win back the trust of people in Wigan, Workington and Wrexham." A YouGov poll shows that Nandy is the first preference for 6% of partymembers. Getty The battle to replace Jeremy Corbyn as Labour leader Rebecca Long Bailey A key ally of the current left-wing leadership of the party, the Salford & Eccles MP is viewed in some quarters as the natural successor to Mr Corbyn and describes herself as a “proud socialist”. Highly regarded by the shadow chancellor, John McDonnell. She won also won plaudits for her performance filling in for Corbyn both at prime minister’s questions and during the general election debates. The shadow business secretary grew up by Old Trafford football ground and began her working life serving at the counter of a pawn shop. Launching her leadership bid, Long Bailey said the party needs to make the positive case for immigration as a "positive force." She also broke with Corbyn over Trident, saying "If you have a deterrent you have to be prepared to use it." PA The battle to replace Jeremy Corbyn as Labour leader Angela Rayner - Deputy leadership Shadow education secretary Angela Rayner has joined the contest for deputy leadership of the party. After ruling herself out of running for the leadership, the Ashton-under-Lynne MP launched her bid for deputy warning that Labour faces the "biggest challenge" in its history and must "win or die." She is close with leadership contender Rebecca Long Bailey PA The battle to replace Jeremy Corbyn as Labour leader Rosena Allin-Khan - Deputy leadership Shadow sport minister Rosena Allin-Khan said Labour need to listen with "humility" to lost voters as she launched her bid for the deputy leadership. Writing in The Independent, the MP for Tooting refelcted: "We shouldn’t have ignored the warning signs in Scotland, and now we’ve paid the price in northern England, across the midlands and in Wales." PA The battle to replace Jeremy Corbyn as Labour leader Dawn Butler - Deputy leadership Shadow women and equalities secretary Dawn Butler was first to announce her bid for the deputy leadership. The Brent Central MP has served in Jeremy Corbyn's shadow cabinet since 2016 PA The battle to replace Jeremy Corbyn as Labour leader Ian Murray - Deputy leadership Labour's only MP in Scotland said that the architects of the party's "catastrophic failure" in the December election can not be allowed to lead the party forward PA The battle to replace Jeremy Corbyn as Labour leader Richard Burgon - Deputy leadership Shadow justice secretary Richard Burgon is standing as a continuity candidate, flaunting his loyalty to Jeremy Corbyn and saying it is wrong to blame the current leader for the election defeat PA

In a letter to Ms Nandy, Ms Long-Bailey, and Sir Keir, the Liberal Democrats’ spokesperson for constitutional affairs Wendy Chamberlain, claimed the last three years demonstrated “politics isn’t working for people”.

“It is broken,” the MP added. "Now is the time to hit the reset button.”

Citing the results of December’s general election, she added: “The Conservatives, despite only getting 44 per cent of the votes, entered the House of Commons with 56 per cent of the seats.

“14.5m people have an MP they didn’t vote for while 71 per cent of votes were ‘wasted’. In Scotland, the situation was even worse, with the SNP securing 80 per cent of the seats from 45 per cent of the popular vote.”

“It is no wonder that people feel they have little or no influence on decision-making today. Our democracy doesn’t need piecemeal change. It needs an urgent and radical overhaul at all levels.

“There are many issues we disagree on. But progressives right across the UK, aside from Labour, agree that we have a decaying electoral system that shuts out too many from our democracy.”

Claiming Boris Johnson cannot be trusted to reform “our broken politics”, she continued: “It therefore isn’t good enough for the next Labour leader to sit on their hands and do nothing. It is past time Labour joined the progressive alliance in favour of electoral reform.

“So far in the Labour leadership contest, electoral reform has been dangerously absent.”

At the 2019 election, Labour said it would hold a constitutional convention in power that would look at the voting system in the UK – but it stopped short of explicitly mentioning proportional representation.