Gimmicky policies, horrible inefficiency and factional promotions are among the catalogue of errors behind Labour’s dismal performance at the general election, according to party members.

The damning comments on Labour’s campaign form part of an early release of views gathered by a team headed by the former party leader Ed Miliband consisting of MPs, union leaders and party members. They have tasked themselves with analysing Jeremy Corbyn’s campaign and suggesting ways the party might find a path back to power.

More than 8,000 people have replied to the nationwide call for members’ experiences and reasons that led to Labour suffering its worst defeat since 1935. A full analysis of the findings will be conducted by the Labour Together Review commission after it closes on 21 February.

Comments received so far include that party’s free broadband commitment felt “gimmicky and distracting” for voters. Another member who responded said they thought promotions to positions of authority were “based on nothing more than factional loyalty”.

One supporter said the strategy of targeting elites was seen as “Trumpian” by voters. “Feel that our rhetoric around ‘elites’ and who we didn’t like or support made us look negative and aggressive,” they said.

A phone system was also “down at the start” of the campaign and an online uploading platform described as “clunky”. One team member said: “It crashed several times and this whole area was the most stressful aspect of running the campaign.”

Speaking at a campaign event in Oxford, Rebecca Long-Bailey said she didn’t think voters had rejected socialism at the general election, and that she would never apologise for the Labour manifesto. “I spent the last four years writing the policies that were contained within that manifesto … I thought it was the most hopeful manifesto I’ve ever seen.”

She asserted her commitment to bringing academies back into local authority control, repealing the 2010 Health and Social Care Act and ensuring the rights of EU workers after Brexit.

Reports over the weekend suggested some Labour MPs were threatening to quit the party if Long-Bailey is chosen as leader, and she emphasised the need for unity between all sides of the party. “We haven’t been a unified party, and whoever the leader becomes we have to have a united party going forward because divided parties don’t win general elections. Whether you’re a Labour member or a Labour MP I would expect you to support our chosen leader.”

Shabana Mahmood MP, one of the review commissioners and a member of Labour’s national executive committee, said: “[It is] still very early days, and we’re encouraging as many Labour party members as possible to take the survey and share their views, alongside our plans to listen to voters in seats we lost and need to win to form a government, many responses so far reflect the big issues of this election: leadership, Brexit, antisemitism and the role of media.

“As the review progresses we want to get a much deeper understanding of some of the lessons this provides for the future. Further detailed in depth analysis and listening to MPs that won, and defeated MPs and candidates, as well as the wider membership and the public will enable us to do this.”

Also on the review team are Miliband, Lucy Powell MP, James Meadway, a former adviser to shadow chancellor John McDonnell, the general secretary of the TSSA union, Manuel Cortes, and Jo Platt, the former MP for Leigh.

The review team met for the first time earlier this month. As well as the survey, they are holding listening events in heartland seats, examining the ground campaign, analysing the role of Facebook and social media, and looking at the part trade unions played.

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Each defeated Labour MP has been written to for their opinions on the election, and Labour candidates in the 124 seats the party must win to form a majority, according to analysis by the Fabian Society. The final document will also suggest ways the party can win again in the future, after suffering four election losses in 10 years.

There were some positive views among the responses, with praise for the event pages for members and the Organise app, which had allowed people to communicate well. Activists’ individual efforts were also recognised, with appraisals such as “everyone did their best”.

Quick guide Who do senior Labour figures in 'red wall' seats want as leader? Show Hide • The “red wall” was a huge block of Labour-voting constituencies stretching from north Wales into Merseyside, through Greater Manchester along the Midlands and up to the north-east. The origin of the term is unclear but some believe it was first used in 2019. • Thirty-three Labour leaders spoke to the Guardian and all but three supported Sir Keir Starmer or Lisa Nandy to become the party’s next leader. All of the 33 local authority areas voted for Brexit in 2016. • Of those who would disclose their least favourite candidate, all but two said Rebecca Long-Bailey. The other votes were for Jess Phillips and Emily Thornberry. • Labour leaders in six of the 10 longest-held Labour seats that fell to the Tories said they were backing Starmer or Nandy. They are the Labour leaders in Rotherham, Newcastle-under-Lyme, Leigh, Bassetlaw, North East Lincolnshire and Bolsover. The other four leaders had not responded to requests for comment.

The review was heavily criticised when it launched in late December for the involvement of Miliband and Powell, who lost the 2015 general election. Powell, who represents Manchester Central, was Miliband’s campaign manager.

She has previously defended their roles, suggesting Miliband retained his Labour seat in the “red wall” as others fell to the Tories; has been campaigning in the traditional heartland of Doncaster regularly for the past four years; and has as much to offer “as the next person”.

They are not due to recommend a leadership candidate to succeed Corbyn.

Their report comes as Labour leadership candidates were presented with a second analysis of the election defeat from Europe for the Many, an organisation that brings together academics and campaigners. They suggest the party will not win the next election without regaining socially conservative voters but warned achieving that presents Labour with a serious challenge.

Their report, The Devastating Defeat, found that in the 2019 election, voters focused on values and identity over economic policies, which advantaged the Tories, particularly in ex-heartland seats. But any rush to recapture socially conservative voters should not lead to Labour imitating Tory policies on immigration and law, they warn.

This could create difficulties in managing Labour’s membership, and previous attempts to become more authoritarian – citing Gordon Brown’s “British jobs for British workers” – had lacked credibility.

Abandoning all discussion of rejoining the EU was also essential for the future electoral success of Labour, the report said.

Bridget Phillipson, Labour MP for Houghton and Sunderland South, said: “To win over voters who are less socially liberal than Labour is today, but more economically leftwing than the Tories, we should not impersonate them.”

Luke Cooper, an associate researcher at the LSE, said: “Brexit has created a really tough situation for Labour. By making values and identity the central questions of the day, it has broken the party’s traditional electoral coalition.”