Former cabinet colleagues Andy Burnham and Yvette Cooper besides Chuka Umunna and Liz Kendall were in the race for Labour’s leadership. The winner will be announced on September 12 before the party conference.
Health spokesman Mr Burnham said the party must support the “aspirations of everyone”, while shadow home secretary Ms Cooper said it must promise “hope”. His main rival Cooper has pledged to “make life better for families” – and conceded that Labour lost the General Election because it didn’t convince voters it “had the answers”.
In an article for the Daily Mirror, Ms Cooper wrote: “Labour needs to be bigger in our appeal, bolder in our ambitions and brighter about the future. Going back to the remedies of the past, of Gordon Brown or Tony Blair, won’t keep up with the way the world has changed. But for many people it wasn’t enough to give them hope and confidence we could match all their ambitions for the future.
“And when there’s too little hope, optimism or confidence, the politics of anger, fear and division takes over – that’s what the Tories, the SNP and Ukip all exploited and campaigned on in this election.
“The fracturing of politics reflects the fracturing of our country and our communities. Divided between rich and poor, north and south, city and small town. And it leaves Britain a darker, narrower place. But that’s why Labour needs to be bigger in our appeal, bolder in our ambitions and brighter about the future.
“Going back to the remedies of the past, of Gordon Brown or Tony Blair, won’t keep up with the way the world has changed. We need a Labour Party that moves beyond the old labels of left and right, and focuses four-square on the future. Credible, compassionate, creative, and connected to the day-to-day realities of life.”
Burnham and Cooper’s announcement came hours after Labour’s ruling National Executive Committee agreed a four-month campaign to find a new leader and deputy leader under the new one-member-one-vote system adopted by the party last year.
Acting leader Harriet Harman said: “The general election saw the Labour Party suffer a serious defeat, and over the coming weeks we need an open and honest debate on the right way forward.
“Our challenge now is to use this time to listen and learn, to elect a new leader and deputy leader who will rebuild the Labour Party in order to take the fight to this Tory Government and to stand up for Britain.”
In a video message announcing his candidacy, Burnham take a swipe at shadow education secretary Tristram Hunt, who has spoken of the need for the party to appeal to the “John Lewis couple” who shop in smart department stores, as well as its more traditional supporters.
Burnham said: “The party that I love has lost its emotional connection with millions of people. The way to get it back can’t possibly be to choose one group of voters over another – to speak only to people on zero hour contracts or only to shoppers at John Lewis.”
Burnham said he wanted Labour to “speak for everyone and for the whole country” and address voters’ aspirations in the way it did in 1997.
He added: “Our challenge is not to go left or right, to focus on one part of the country above another, but to rediscover the beating heart of Labour.
“And that is about the aspirations of everyone, speaking to them like we did in 1997. And it needs a leader whose voice can carry into all the nations and regions of the UK, be heard in every home. Someone who people can relate to, who understands their lives.
“I am that person. I can unite this country. And that’s why I am standing to be leader of the Labour Party.”
Acting leader Harriet Harman pledged an “open and honest” debate on the future, as she set out the election timetable.
“Our challenge now is to use this time to listen and learn, to elect a new leader and deputy leader who will rebuild the Labour Party in order to take the fight to this Tory government and to stand up for Britain,” she said.
Mr Miliband resigned last week after the party was left with just 232 seats, having sustained heavy losses at the hands of the SNP and failing to make ground in England. The Conservatives defied the opinion polls to win an overall majority.