The interim Labour leader has admitted that even people who supported Labour in the General Election were relieved that the party did not win.
In an interview with The Independent, Harriet Harman said concerns about the party's leadership and economic competence hindered Labour's success.
Labour was left with just 232 seats after the General Election - the party's lowest level since 1987. Its Scottish seats were devoured by the SNP, while Ukip damaged the party in the north of England and it failed to win back southern voters.
Reflecting on this poor performance, Harman told The Independent:
Sometimes after an election, you get a sense that people think ‘Oh my God, that is terrible, what a disaster.’ A lot of people felt that because we got nearly 40,000 new party members who were very disappointed.
But there is an even greater number of people, even though they were not enthusiastic about David Cameron or the Tories, who feel relieved that we are not in government. We have got to address it. It was not a blip.
Harman has commissioned Deborah Mattinson, Gordon Brown's former pollster, to investigate why voters turned away from Labour in the election.
She said it was in the party's interests to have "some turbulence" now with thorough analysis of what went wrong, instead of "paper[ing] over the cracks" for party unity.
"When you change the captain of the ship," she added, "you should look at the direction it is going in".