Speaking at a HuffPost UK fringe meeting at the Labour conference in Liverpool, Nandy said that it was “really important” that Corbyn had a mix of elected and appointed frontbenchers to show “he means it” about unity.
The former Shadow Energy and Climate Change Secretary added that the leader had to prove his Shadow Cabinet was “a genuine team with trust” and “people in that room who aren’t reliant on the leader for patronage”.
And she warned that unless Corbyn and his team admitted how far Labour was behind in the polls, the party could end up nearly wiped out like the Liberals in the early 20th century.
In a wide-ranging inteview, she warned her party that it had to accept the voters’ verdict on Brexit, called for a higher minimum wage for care workers and urged new qualifications requirements for migrants.
Giving her clearest hint yet that she will not be rejoining the top team, Nandy said that it was “a huge opportunity to be an MP on the backbenches”, pointing out Tom Watson and Stella Creasy achieved more outside the frontbench in the last Parliament.
The Wigan MP, who has been tipped as a future leader herself, also refused to rule out running for the top job one day, but stressed what was important was a collective leadership rather than one individual.
Following his re-election on Saturday, Corbyn persuaded the ruling NEC to delay until November at the earliest any decisions about giving MPs a say over who should be in his Shadow Cabinet.
John McDonnell confirmed today that it would be ‘weeks’ before any such decision, a move that prompted a backlash among some MPs who said it undermined the leader’s vow to “wipe the slate clean” after the bitter leadership battle with Owen Smith.
Nandy said that it had been a mistake for Ed Miliband to scrap Shadow Cabinet elections because it resulted in a leader who was surrounded by those who agreed with him.
“I saw in the last Parliament how unhelpful it is then when you don’t have people in that room who aren’t reliant on the leader for patronage because you don’t get that level of challenge.
“So for me there is something potentially quite important about saying we need people who are in the Shadow Cabinet who have a mandate from somewhere that isn’t the leader, who feel free to speak their minds.
“I think if Jeremy were to accept that proposal…to have a mixture of elected and appointed representatives in the Shadow Cabinet, it would be a significant step forward. It would tell a lot of those Members of Parliament who lost confidence before that he means it when he says that everybody’s welcome.”
Nandy, who backed Owen Smith’s campaign for leader, stressed that she was one of 14 MPs who refused to take part in the ‘vote of no confidence’ in Corbyn in the summer.
But asked if the restoration of some kind of MPs’ say over the top team was a ‘red line’ for her, she replied: “I think Shadow Cabinet elections is really important actually. It’s become important because it’s become very symbolic”.
Nandy said she was “still trying to digest” what Corbyn’s re-election meant for the party’s direction, but made clear that he had to reach out not only to all wings of Labour but also to all types of voter, including Tory voters.
”I think the thing for me is about what constructive role I can play in this party. And whether the Shadow Cabinet is a genuine team with trust that works together with different levels of challenge and different points of view to try to compromise in an open and respectful way.
“Or whether it’s a much smaller group of people who share a worldview and a set of policy ideas who are working to make that happen. The former is the only way I think.”
Nandy hit out at senior figures in the party who denied that Labour was doing badly in the polls and in real elections, and said Corbyn had to acknowledge how far he was from power.
“The other thing that is incredibly important for me and many other MPs is we start with an acknowledgement of the scale of the challenge,” she said.
“Even as late as yesterday there were senior members of the leadership out saying we were ahead in the opinion polls, and we were doing well and just needed to go back to what we were doing before.
“I just don’t agree with that because I can feel the public moving away from us, even in towns like mine where people have a strong commitment to social justice and have voted Labour consistently for 100 years.”
A new BMG/HuffPostUK opinion poll on Sunday found that 70% of the public preferred Theresa May and Philip Hammond as Prime Minister and Chancellor. Just 30% preferred Corbyn and John McDonnell.
The former shadow minister said that in February Labour hit its lowest level in the polls for a Labour opposition since the 1930s. “And you can feel it with the public and it’s still happening now. The problems we had were real.”
“We have got to take that seriously. Brexit, Scotland, these were warnings to us. But there is another warning from history as well and that is the fate of the Liberal Party.
“If you stand still while the world around you changes, then it doesn’t matter whether you are radical because you cease to be relevant and then you’re not a force any more.”
In 2015, Nandy came under pressure from author Owen Jones and others to stand for the party leadership, but with a baby just four days old on the day of the general election she said it was impossible.
She said Jones “texted me about 100 times that week”. She joked: “And then he took to Twitter to try and mobilise his army of followers to try and browbeat a new mum into standing for the leadership of the Labour party, as I told him by text!”
When asked if she had ruled out ever becoming Labour leader, Nandy replied: “I didn’t come into politics to be leader of the Labour party, that’s the honest truth.
“The truth is if we are going to face up to the challenges we have got and we are going to build an underlying public philosophy and a vision for the future as it could be, it’s not going to come from me, or Dan Jarvis, or Chuka, sitting in a room by ourselves working up our grand vision for the future.
“That’s really the challenge. It’s not who gets to wear the biggest badge, it’s who can play a part when and how and how we build a better team in the Labour party.”
Nandy added over the last six years she had seen that “the presidential model we have of leadership is broken”.
“This is not criticism of the individuals involved, I worried a lot in the 1990s about the sort of movement that grew up around Tony Blair as an individual and I worry a lot about the way we seem to be doing that with Jeremy as well.
“I think he knows and I think Tony Blair knew as well, to that one man alone, to quote Ernest Hemingway, is not enough.”
One audience member at the HuffPost fringe pleaded with Nandy to rejoin Corbyn’s team, saying he was one of many party members who were tempted to “walk away” from the party if she didn’t go back to the Shadow Cabinet.
“What you’ll see over the next few weeks, Jeremy is obviously going to have to make a series of decisions about who he wants in his Shadow Cabinet and on his front bench,” Nandy replied.
“And then everybody who is asked is going to have to make a decision about what to do next. All I would say is that during the horrible events of this summer as people were resigning or not resigning, there were far too many people who had something to say about everybody else and too little to say about themselves.
“I think going forward what we’ve got to do is respect the decisions that people make to be on the front or backbenches. The truth is you can make a huge difference from the frontbench…but it’s also a huge opportunity to be an MP for Labour on the backbenches.
“You can delve into issues, you can work cross party to try and achieve change. The two people that I think probably made the biggest impact in the last Parliament for Labour were Stella Creasy on loan sharks and Tom Watson on News International, from the backbenches.
“Whatever we all decide to do, the important thing is we are constructive and collaborative and we make an impact.”
She also said that Yvette Cooper had warned Ed Miliband back in 2011 not to abolish Shadow Cabinet elections because it would undermine the number of women in the top team.
“Yvette Cooper got up at a meeting of the Parliamentary Labour Party when we were about to change the rules on Shadow Cabinet elections. She pointed out that what we were about to do was going to worsen the representation of women on the front bench.”