Jeremy Corbyn has insisted his reshuffle made Labour "stronger" despite being hit by a fresh resignation and accusations of "incompetence".
The Labour leader defended the shake up of his top team as it emerged that Alison McGovern was stepping down from heading a party poverty review.
The Wirral South MP has been infuriated by shadow chancellor John McDonnell's jibe that the Progress group - which she chairs - is "hard right".
She is set to spell out her reasons in an interview on the BBC's Sunday Politics, potentially fuelling a row between the Labour leadership and the broadcaster.
Mr Corbyn's office has filed a formal complaint after accusing the BBC of "orchestrating" the on-air resignation of Stephen Doughty from the front bench just before Prime Minister's Questions on Wednesday.
However, shadow civil society minister Anna Turley has said she had "no problem" with the corporation's actions.
Jonathan Reynolds and Kevan Jones also quit as shadow ministers citing policy differences with the leader and unfair treatment of sacked Europe spokesman Pat McFadden and shadow culture secretary Michael Dugher.
In an interview with The Sunday Times, McFadden accused Mr Corbyn and Mr McDonnell of an "attempt to demonise and delegitimise people and stop other voices being heard".
"The use of rhetoric like that is not what Jeremy promised when he took over.
"He said he would practise a kinder politics without personal attacks."
The promotion of Emily Thornberry to shadow defence secretary, replacing Maria Eagle, who supports the nuclear deterrent, has fuelled speculation that Mr Corbyn is planning to bring the party's position in line with his own unilateralist view.
Ms Thornberry and former London mayor Ken Livingstone, both opponents of Trident, are now jointly overseeing Labour's defence policy review.
Former soldier and Barnsley MP Dan Jarvis has said he would be "deeply uncomfortable" being a Labour candidate in 2020 if the party's manifesto pledged to get rid of the deterrent.
Mr Jones, a long-serving member of the defence team, told the Sunday Telegraph he viewed Mr Livingstone's influence as damaging. The close Corbyn ally recently suggested the UK could leave Nato, and argued that Russian president Vladimir Putin does not pose a military threat.
"Ken Livingstone hasn't got a clue what he is talking about. He is clearly not aware of the massive investment that Putin is making in not only upgrading Russia's nuclear capability but actually expanding it," Mr Jones said.
In an article for the Observer, Mr Corbyn tried to turn his fire on the Tories, accusing David Cameron of attacking democracy by cutting public funding for political parties and slashing the number of Westminster seats.
"For all the media sound and fury, last week's shadow cabinet reshuffle has made us a stronger, more diverse and more coherent leadership team," he wrote.
"Along with the huge increase in our party membership in the past six months, it will help make Labour a more effective champion of the people who need us to give them a voice, to win elections and change our country for the better."
Meanwhile in a possible sign of manoeuvring against Mr Corbyn, shadow work and pensions secretary Owen Smith has voiced interest in becoming leader.
"I don't think there's any vacancy right now," he told the New Statesman. "But I think any politician who comes into this to want to try and change the world for the better ... I think they're either in the wrong game or fibbing if they don't say, 'if you had the opportunity to be in charge and put in place your vision for a better Britain would you take it?'
"Yeh, of course, it would be an incredible honour and privilege to be able to do that."