Liz Kendall has said she is “never going to leave the party I love”, after a major Labour donor this week floated the possibility of a potential split if Jeremy Corbyn is elected leader. The leadership contender said she did not believe Labour was headed to a major split, as happened in 1981 with the formation of the Social Democratic Party, and would not leave if it did happen.

John Mills, who donated well over a million pounds to Labour under Ed Miliband, predicted that there would be “some sort of split” if Corbyn won.

However, in an interview in today’s Independent on Sunday, Kendall rubbishes the idea that she would be on her way out of a Corbyn Labour Party, despite having said that she would not serve on his frontbench. She said:

“I am a loyal person: I am never going to leave the party I love, but Jeremy’s politics isn’t right for Labour or the country so I wouldn’t serve in his shadow cabinet if he were to be elected.”

“That’s not what I want, and that’s not what I believe will happen. I can no more leave the Labour Party than leave my own family. And you never stop fighting for what you believe in. I won’t quit. I won’t quit this race and I’ll never leave the Labour Party.”

Kendall did, however, say that if Corbyn becomes leader in September, Labour “will be out of power for a generation and that will be a betrayal of all of the people we are in politics to serve”. She expands on that idea in an Observer article today, where she writes that “I don’t think it’s principled to give up on electoral victory to make ourselves feel good.”

In the piece, she rejects the idea that this contest is a choice between having principles and giving them up in the pursuit of power. She says:

“Jeremy Corbyn and his supporters do not have a monopoly on principle. Many do, indeed, have firmly held principles, but they are not the only ones in our party or our movement.

“This contest isn’t a choice between heartless pragmatism to win power and purity out of power. I’ve spent this campaign setting out the principles that drew me into the Labour movement and which I’ll keep on fighting for: ending inequality in the early years so every child has an equal shot at life; tackling low pay to build a real living-wage society and giving public sector workers the pay rise they need and deserve; and devolving decisions to communities and councils so people have power and control over their services and lives.

“These are our Labour values.”

Kendall has come under pressure to withdraw from the race this week, with some arguing that she should throw her weight behind another moderate candidate in order to stop Jeremy Corbyn. She has already dismissed these calls, and today has received support from Corbyn’s campaign. A spokesperson for the left wing candidate said earlier that the calls were wrong:

“Calls on Liz Kendall to withdraw from the leadership race are wrong and she is right to reject them. Liz Kendall represents a body of opinion in the party that is as entitled as any to a voice in this contest, particularly given that voting in this election is based on a transferable vote – so that staying in or pulling out has no impact on the final outcome. It would narrow the debate if the field of candidates were reduced. All strands of opinion must be heard and Liz should remain in the race.”