One of the senior staff of Jeremy Corbyn, who drafted Labor's last manifesto, announced his resignation.
Andrew Fisher, head of the Policy Department, will leave his post at the end of the year, "to spend more time with his young family".
The Sunday Times claims that Mr. Fisher warned that Mr. Corbyn would not win the next parliamentary elections.
Mr. Corbyn confirmed that Mr. Fisher left office and said it was a "very stressful and busy job". "
Mr. Fisher is said to have announced his intention to resign, according to a Sunday Times release.
The newspaper reports that he criticized Mr. Corbyn's team for their" lying blizzard. " Mr. Corbyn said to opposite BBC broadcast Andrew Marr: "I think he said that because at the time he was extremely concerned about what was going on in the discussions in the office."
The Labor leader described Mr. Fisher as a "great friend" and someone with whom he had worked for fifteen years, including Mr. Corbyn's time as a Member.
"He is a great writer, he is a great thinker and He has done a lot of work in the party."
"We get along very well and he has promised that he will be with me in political matters in the future
In a statement by Fisher, BBC political correspondent Iain Watson said he wanted to "prioritize" his wife and little son. www.germnews.de/archive/dn/1996 /03/27.html Mr. Fisher said he was "very proud of what we have achieved together."
But he added: long hours, stress and strains that inevitably come from working in that high pressure environment means that I have failed to reconcile my obligations to my wife and young son.
"After four years, I now decide to prioritize. I will stay in all the autumn elections, but leave by the end of the year. "
It happened after Labor's deputy leader Tom Watson had called on Friday for a fall attempt at the start of the party's annual conference to reach an agreement.
Mr. Corbyn later proposed to reconsider the role, and his proposal was supported by the ruling NEC.
Since then, he has told the Sunday Mirror he wants the party's two deputy leaders to have diversity in our society. "
Mr. Corbyn told the newspaper a deputy chairman was a woman.
He added," Tom is the elected vice chairman of the party and therefore plays an important role.
"I work with him and he is very good at promoting media reform, online gambling, and the way sugar damages our lives."