John Lansman (left) has admitted Corbyn's party has an anti-Semitism issue (Image: GETTY/BBC)
Mr Lansman, who is Jewish, heads up the powerful grassroots campaign group which helped secure Mr Corbyn became Labour leader back in 2015.
However, now the close ally of the Islington North MP has added to Mr Corbyn’s anti-Semitism headache by confirming his social media was full of racist posts from friends over the summer period.
Speaking to the Financial Times, he said: “I’ve had times when I’ve woken up and I look at my iPad.
“There’s one morning I remember, not many weeks ago, when I was just horrified at things on my Facebook page from people who I regarded as friends.”
The crisis in Labour came to a head after the party's ruling body did not accept the International Holocaust Remembrance Alliance’s (IHRA) definition of anti-Semitism in July.
Since then a number of accusations of racism in the party have emerged.
In one such instance a Labour Councillor in Bognor Regis was suspended after allegedly saying Talmud Jews need “executing”.
He also appeared to share a video titled “Jewish ritual - they drink blood” which promoted the ancient anti-Semitic blood libel.
Jeremy Corbyn's anti-Semitism crisis came to a head in July (Image: GETTY)
There have been protests in London in anger at Jeremy Corbyn's failure to tackle the issue