Labour deputy leader Tom Watson has joined calls for a senior official at the centre of an anti-Semitism row to step down from the party's ruling body.
Mr Watson said he hoped Christine Shawcroft would "explore her own conscience" and voluntarily give up her position on the national executive committee (NEC).
He also said he believed it was "highly likely" that former London mayor Ken Livingstone - who remains suspended over comments suggesting Hitler supported Zionism in the 1930s - would be permanently expelled from the party.
His intervention came as an opinion poll found around three quarters of Labour members believed the party's problems with anti-Semitism were being exaggerated to damage Jeremy Corbyn.
The You Gov survey for The Times found that just 19% thought it was a serious issue while 77% believed it was being used to undermine the leader or stop criticism of Israel.
The findings follow a tumultuous week that has seen fresh recriminations within the party as well as a protest outside Parliament led by Jewish leaders.
Ms Shawcroft was forced to quit as chairwoman of the party's disputes panel after it emerged she had opposed the suspension of a council candidate accused of Holocaust denial, although she retains her place on the NEC.
She caused further anger with a Facebook posting - subsequently taken down - claiming the row was being "stirred up to attack Jeremy, as we all know".
Although she has since said that she was "deeply sorry" to the way she handled the complaint of Holocaust denial and that she will not stand again for the NEC when her post comes up for re-election in the summer, Mr Watson said she should go now.
"There is a problem with Christine Shawcroft who tried to hold up an inquiry into someone accused of Holocaust denial and then said the accusations were whipped up against Jeremy," he told the BBC Radio 4 Today programme.
"I think that is disgusting. I actually think it undermines Jeremy. I am afraid she is elected by our members. I am not in a position to remove her from the committee and neither is Jeremy.
"I hope she can explore her own conscience and realise the damage she has done to her own party and to Jeremy personally and make the right decision."
Mr Watson also called for the party's new general secretary Jennie Formby to ensure there was a swift resolution to the case of Mr Livingstone - a long-time ally of Mr Corbyn who was first suspended in 2016.
"He is subject to disciplinary procedures. Given what he has said I think it is highly likely he will (be expelled). He is entitled to due process on that. I just hope that the new general secretary will make sure that that inquiry is very quick," he said.
On Friday, Mr Corbyn issued a Passover message insisting he is an "ally" in the fight against anti-Semitism.
But a Jewish Labour peer said the party leader had "encouraged and endorsed" anti-Semites.
Lord Winston said hostility to Jews has "infected the Labour Party so it's become endemic".
- YouGov interviewed 1,156 Labour members between Tuesday and Thursday.