Labour leadership candidate Liz Kendall took on rival Andy Burnham on Wednesday evening, telling him that the country not the party should be the priority for Ed Miliband's successor.
Yvette Cooper, Jeremy Corbyn, Kendall and Burnham went head-to-head on Wednesday evening in a live televised debate hosted by BBC Newsnight.
Burnham, Kendall and Corbyn all suggested the party should have a chance to get rid of them before the 2020 general election. However Cooper appeared less keen on the idea.
For the most part, the four candidates engaged in friendly debate. However there was a frosty moment when Burnham said the "party should come first" when he was asked if he would reopen the leadership before 2020. Kendall quickly interjected to say the "country should come first".
Kendall, when asked whether she would be willing to resign if it looked as if Labour would not win the next election, replied: "Yes".
"More than anything, I want Labour to win so we can change the country. Now, I think I am going to be the Labour leader that the Tories fear and that's right because we need to win. We are forgetting our winning ways as a party. It has been too long since we won those major elections," she said.
Kendall, added that if the party thought she was "not doing a good enough job" it should be easier to kick her out.
Burnham said he was confident he would lead Labour to victory in 2020, but said "of course" the party should be able to get rid of him if it was not happy. "Yes is the answer to your question," he told BBC presenter Laura Kuenssberg. "I wouldn't do anything to harm the interests of the Labour Party".
Corbyn, the leftwinger who made it onto the ballot with seconds to spare, said there should be a leadership election every "one or two years".
However Cooper appeared less impressed with the idea of opening up the issue of the leadership two or three years before the next general election. "The party already has rules to do that kind of thing," she said. Cooper also said it seemed wrong to ask people standing in the leadership contest to decide what the leadership rules were.
"We have to make sure we have a really good leadership debate right now," she said. "The party can choose the right person to be Labour leader and also be a Labour prime minister." Cooper said the party should focus on "holding the Tories to account" and "holding David Cameron to account".
Toby Perkins, the chairman of Kendall's campaign commented after the debate: "You know you've got line of the night when others claim they said it: 'definitely Liz who said country comes first'."
During the debate the candidates were quizzed on immigration and welfare. Cooper, who had to take time off work due to illness 20 years ago, told the audience in Nuneaton that "as a result, I would never say that people who can't work are workshy".
Cooper also said the time had come for the Labour Party to elect a woman leader. "For the Labour Party which has campaigned for women's equality for over a century, it would be fantastic for us to smash that final glass ceiling and elect a Labour woman leader of the party and a Labour woman prime minister as well," she said.
But she refused to be drawn on whether she would support Kendall, the other female candidate, if she did not win, saying "I am not backing anybody else."