Labour’s deputy leader Tom Watson has said a local party branch is being investigated over its alleged treatment of MP Luciana Berger.
Mr Watson accused Liverpool Wavertree branch members of “bullying” the MP and trying to drive her out.
The branch scrapped a meeting to discuss a no-confidence motion in Ms Berger after an angry backlash.
It said it had “no control” over motions tabled by members and rejected claims of bullying and anti-Semitism.
Speaking on the BBC’s Andrew Marr Show, Mr Watson said: “That motion should never have been moved in her local party, the meeting to hear it should never have been scheduled.”
He said Mr Corbyn had “made it clear these things are not done in his name”, and they “are not helping him, they are harming the reputation of the Labour Party”.
Mr Watson added: “I don’t want any MP or any member of the Labour Party to feel they’re being bullied and driven out, and what’s happening to her is completely unacceptable, which is why I called for the local party to be suspended.”
Labour’s general secretary Jennie Formby said there was “no constitutional basis” on which to suspend the local party, but Mr Watson confirmed that Ms Formby was “investigating members in that constituency”.
In a statement, the leaders of Wavertree Labour Party said: “We as an executive have always and continue now to express total solidarity with Luciana as a victim of misogyny and of anti-Semitism – coming mostly from the far right.
“Our chair is himself Jewish and the suggestion that the CLP (Constituency Labour Party) Executive is in any way a party to bullying and anti-Semitism is a false and slanderous accusation.”
They defended scheduling a meeting to discuss the no-confidence motions, saying it was “to give our MP the maximum opportunity to take part when the motions were debated”.
The executive added that they “strongly reject the media inaccuracies and the accusations of political bullying, for simply adhering to party rules and doing our jobs”.
Ms Berger, who is Jewish, has been an outspoken critic of the party’s handling of anti-Semitism allegations and its stance on Brexit.
The motion that was pulled criticised her for “continually using the media to criticise” Jeremy Corbyn.
Shadow chancellor John McDonnell sparked a backlash from some Labour MPs after he suggested on Friday that the move against Ms Berger was more to do with her disloyalty to the leadership than anti-Semitism.
He urged Ms Berger to publicly reject claims she supported a Labour “breakaway”, amid media speculation MPs disenchanted with Mr Corbyn’s leadership were planning to form a new party.
On speculation about Labour MPs forming a new party, Mr Watson said “we are all worried about a breakaway because we need unity in order to win the next general election”.
Speaking more broadly about the abuse MPs have had to put up with amid the “hate-fuelled debate around Brexit”, Mr Watson told Andrew Marr he knew of “an MP who had changed their vote because they were frightened”.