Harriet Harman is stepping down as Labour's deputy leader, she has announced.
She paid tribute to Ed Miliband "for his leadership" and "for his decency, his commitment and his constant striving for a fairer country".
In a speech, she said: "On the resignation of Ed Miliband as leader of the Labour Party I, as his deputy, am stepping forward to be acting leader until a new leader is elected by the party."
She added: "With a new leadership team in place, after what has undoubtedly been a serious defeat, the Labour Party will be best placed to be the strong opposition this country needs - defending our NHS and our public services, and fighting for fairness, equality and social justice.
"That determination will be all the fiercer in the face of this Tory government."
Labour's deputy leader Harriet Harman has questioned whether the Conservatives could form a majority government with any other party.
Harman urged people to treat an exit poll, predicting the Tories would be the largest party, with caution, saying there were many seats which were going to be "very close".
She told ITV News: "If the exit poll is right...what it shows is the coalition led by David Cameron has more or less lost its majority.
"We'll have to see whether the new House of Commons that's been newly elected will give David Cameron a majority."
"I think it's far too early to say."
Shadow Deputy Prime Minister Harriet Harman has claimed that the Liberal Democrats are trying to pretend that they haven't been part of government for the past five years - and that they aren't responsible for the country's 'problems'.
Labour's women's manifesto is "showing women that we are on their side and will stand up for them in government", Harriet Harman said today.
Launching the document at Stockwell Gardens Nursery in south London, the deputy party leader said the document entitled A Better Future For Women, was intended to show politicians were "there for women as well as men".
As far as Labour's concerned you're not on the margins tou're absolutely central. We know that actually the bedroom tax hits more women then me. We know that one of the things that drags down women's pay is that more women are on zero hours contracts.
People will remember that it was Labour that set up those Sure Start centres, that brought in the child care tax credit...They know that the government that is going to back childcare is Labour - never the Tories not the Lib Dems.
Ms Harman was joined by Labour's shadow home secretary Yvette Cooper and shadow minister for women and equalities Gloria De Piero as they arrived in the party's woman-to-woman pink bus.
Deputy Labour leader Harriet Harman says no one would believe the Liberal Democrat's manifesto promises because they broke their pledge to protect university tuition fees.
People know that the Lib Dems are every bit as much to blame as the Tories. They have backed the Tories every step of the way while people's living standards have fallen and the NHS has been going backwards.
People know that the Lib Dems' manifesto can't be trusted. They broke the key promises in their last manifesto and are repeating them once again. People will remember the Lib Dems' record on trebling tuition fees, wasting £3 billion on the NHS and increasing VAT, and know their promises for the future can't be trusted. This country needs change - not the same Lib Dem broken promises.
Labour's deputy leader Harriet Harman has denied telling one of the party's female councillors she was "too pretty" for politics.
Karen Danczuk, who has previously hit the headlines for her regular posting of selfies, claimed on Twitter that the Labour equalities spokeswoman suggested she would be more suited to being in all-girl pop group 'Girls Aloud'.
When I first met Harriet Harman she said I was far too pretty to be interested in politics & should be in Girls Aloud. KD
But Ms Harman released a statement saying: "I deny I ever said that and it's inconceivable I would have ever said that.
"I have always believed it's what you do in politics, not what you look like. I have never discouraged a woman from getting involved in politics on the basis of their looks."
Harriet Harman has denied Labour is "patronising" women by unveiling a bright pink "women's campaign" bus to encourage them to vote.Read the full story ›
Deputy Labour leader Harriet Harman will stand in for Ed Miliband at Question Time in the House of Commons tomorrow, Labour has said.
Harriet Harman has again attacked the Daily Mail's coverage of the affiliation between a group she worked with in the 1970s and their links to a paedophile rights group.
Speaking on The Agenda with Tom Bradby on ITV this evening, she said: "The idea that the Daily Mail suddenly comes up with this idea that I'm an apologist for child abuse. I mean, how on earth could I apologise for that?
"It's not true. I went from being a man-hater one minute, according to the Daily Mail, to colluding with dirty old men."
Also on the panel this evening are advertising boss Sir Martin Sorrell, presenter Julia Bradbury and comedian David Schneider.
The Agenda airs at 10.35pm on ITV
Former Paedophile Information Exchange (PIE) chairman Tom O'Carroll told ITV News he is "confident" Harriet Harman was aware the group was represented on a gay rights sub-committee in the late 1970s.
O'Carroll told UK Editor Lucy Manning he did not think Harman had any involvement with PIE "directly or indirectly", adding, "except through her knowledge of the fact that the organisation had a presence within the NCCL" sub-committee.
He said: "She presumably knew that we were affiliated with the NCCL and must have known, I think, that a representative of PIE - for a long time that was myself while she was there - was on the gay rights sub-committee.
"She must of known that, I am confident, because she had regular discussions with her staff, including the person who presided over the gay rights sub-committee, and that person would have talked to her about the proceedings of the committee from time-to-time I'm sure".