The former British shadow health secretary says the right thing for Jeremy Corbyn to do is to "step down with dignity and honour".
Heidi Alexander's comment comes as the British Labour leader says he's ready to "reach out" to his opponents in the party.
He also says he would stand for re-election if challenged.
In an article for the Sunday Mirror, the Labour leader said: "I am ready to reach out to Labour MPs who didn't accept my election and oppose my leadership - and work with the whole party to provide the alternative the country needs.
"But they also need to respect the democracy of our party and the views of Labour's membership, which has increased by more than 60,000 in the past week alone. Our priority must be to mobilise this incredible force to oppose the Tories, and ensure people in Britain have a real political alternative. That is my priority and always will be as leader of our party. Those who want to challenge my leadership are free to do so in a democratic contest, in which I will be a candidate."
Former Labour leader Neil Kinnock says Mr Corbyn should go:
