Deputy Labour leader Harriet Harman at Labour HQ in London yesterday, speaking about how Labour would move on from an election defeat. Photo: PA Wire

Acting Labour leader Harriet Harman and the boss of Britain’s biggest union are seeking to calm a row over the future of the party following its disastrous general election result.

Unite’s general secretary Len McCluskey, who has been involved in a bitter war of words with outgoing Scottish Labour leader Jim Murphy, said yesterday he would not support any move to disaffiliate from Labour and backed the party to “rise like a phoenix” from the ashes of its defeat.

Harman, who said Ed Miliband’s replacement at the head of Labour must appeal to the whole country rather than just the party faithful, insisted that although the role of the unions in deciding the next leader had changed there would be no break with Unite.

Debates about the historic link between the party and the unions have been raging since Miliband steered through reforms last year. Unions gave Labour the bulk of the money the party raised for the general election campaign. Sources told the Press Association that Labour raised £12 million in its unsuccessful attempt to win power, with £9 million coming from the unions.

The amount shows how reliant Labour is for money from the trade unions, backing up the belief that the party would otherwise go bankrupt.

Trade union conferences in the coming months are sure to discuss the relationship with Labour and there are likely to be the usual calls for a re-think of the link.

The head of UK Labour must appeal to the whole country rather than just the party faithful

But McCluskey insisted: “We have no plans to disaffiliate from Labour. The party has never been more united.”

He added that everyone now agreed it was time to debate Labour’s future but he believed there was an “exciting opportunity” for the party.

Divisions over the future of the Labour movement after the election became clear as Mr Murphy declared he was resigning as Scottish leader and delivered a stinging parting shot at Mr McCluskey, describing his support as a political “kiss of death” for the party.

Harman was challenged about the row by journalists at Labour’s headquarters in London and appealed for “cool heads”.

In response to Murphy’s attack on McCluskey, Harman said: “We have had a bitter defeat, we have had a thumping in Scotland. It would be very surprising if some people didn’t, from time to time, express an exasperation and frustration and anger.”

Insisting that the union link would remain, she said: “I don’t think there is going to be a break between Unite or any of the unions that are affiliated to the Labour Party.

“We have had a lot of soul searching to do across all parts of our party and we will have robust discussions. But, no, I don’t think there is going to be a disaffiliation.”

The unions played a key role in Miliband’s election as Labour leader under the old electoral college system which gave them a third of the votes.

Harman stressed that the influence of the unions over the decision on leadership had been altered by the move to a “one person, one vote” electoral system.

The next Labour leader will be elected on September 12, and Harman said the contest should involve a series of “robust, tough, televised hustings which involve the public” with events in battleground areas the party had failed to win.

“Above all, we will let the public in and elect a leader who can lead not just the party but the whole country,” she said. Harman criticised the “cosy” deputy leadership contest which led to her victory.

“We asked ourselves ‘Who do we like?’. That was the wrong question. We should have asked – as we made our choice – ‘Who does the country like?’