Tom Watson has said he will take personal charge of antisemitism and bullying complaints made by MPs to bring them to the attention of the Labour leadership, telling colleagues he will hold the party’s management of the complaints to account.

In a separate attempt to stop further defections, the Guardian understands that Labour could delay the start of re-election battles.

Labour is set to put back the start of the formal MP selection process, due to begin in a few weeks, which could have led to vast numbers of MPs facing deselection.

The party’s governing national executive committee was expecting a paper to approve the start of the process at its next meeting in March, but this is now expected to be delayed for fear that imminent deselection fights will prompt dozens more MPs to quit the party. “We don’t want to further antagonise,” a party source said.

In an email sent before Jeremy Corbyn’s appearance at a meeting of MPs on Monday night, Watson promised to work on the bullying problem.

One Labour source described the step as “effectively creating a parallel disciplinary process”.

Watson said he and his team would now be “logging and monitoring all complaints” so he could raise them himself with the leadership and with the NEC.

He has called on Corbyn to tackle “a crisis for the soul of the Labour party” or risk many more defections to the Independent Group after nine MPs quit the party last week, with at least three citing antisemitism and bullying as their main motivation.

Watson, who has challenged Corbyn directly to be more robust, was also critical on Sunday of Labour’s general secretary, Jennie Formby. “Very patently, the Jennie Formby reforms have not been adequate. They have not succeeded,” Watson said in an interview with BBC One’s Andrew Marr Show.

Watson said in his email, seen by the Guardian: “Over recent weeks a number of colleagues have shared their frustration that incidents of antisemitic, racist abuse and bullying have not been dealt with in an adequate and timely manner or that colleagues have not been informed of the outcome of party investigations.

Anger, denial and prejudice fester on the streets of Liverpool Wavertree Read more

“In response to these concerns, I requested that the general secretary improve procedures by appointing a named member of staff that could be a point of contact for colleagues to raise cases and be updated on progress. Jennie Formby was very clear that she sees it as her responsibility to be your point of contact.”

Watson said MPs should email Formby directly but requested that he also be shown any complaints submitted to her so that he could track their progress.

“As your deputy leader I am deeply alarmed at the amount of abuse that colleagues are receiving from within the party,” he said.

“In order to properly assess and monitor the scale of the problem, I would like to see any issue or complaint you raise with the general secretary. From now on my team will be logging and monitoring all complaints. I will ensure that this information is shared with both Jeremy, the shadow cabinet and colleagues on the national executive committee.”

On Sunday, Watson said he had received 50 complaints about antisemitism from colleagues in the past week, which he had forwarded to Corbyn.

The complaints he had forwarded included Labour members sending tweets linking Hitler and the Rothschilds, accusing Jews of murdering children and questioning whether Jewish MPs and councillors had “human blood”.

All of the cases had been raised by Watson or other Labour MPs over a period of several months, but no action had been reported back to those who had raised the complaints, he said.

Earlier on Monday, Jon Lansman, chair of the leftwing grassroots group Momentum and an NEC member, said antisemitism was a far more widespread problem in the party than he had previously realised and said he felt “regret, sadness and some shame” at the decision of the Jewish MP Luciana Berger to quit the party.