LABOUR MPs, unions and campaigners have urged Sir Keir Starmer to end the “rotten culture of nasty factionalism” in Downing Street.

Senior parliamentarians and the leaders of several affiliated unions told the embattled PM the authoritarian approach is “increasingly unpopular with the public.”

Former shadow chancellor John McDonnell and Mother of the House Diane Abbott, currently suspended from the party, were among 25 MPs who signed a letter dubbed the Restore Labour Democracy statement, alongside the general secretaries of the Labour-affiliated unions Unison, Unite, the CWU, the FBU and Aslef.

Hitting out at the culture within Downing Street and Labour’s ruling team, the letter states: “It’s increasingly clear that a narrow, factional agenda is being imposed upon the party and that this is increasingly unpopular with the public.

“This approach is wrong in principle and damaging in practice. When the Labour Party sidelines its members, it weakens Labour’s roots in our communities, alienates voters, and undermines Labour’s ability to win both people’s trust and elections.”

Labour members and trade unionists were allowed to add their names to the letter from yesterday — the 120th anniversary of the formal adoption of the name “The Labour Party” in 1906.

Labour MP for Leeds East, Richard Burgon, who helped to co-ordinate the statement, said: “Under Keir Starmer and Morgan McSweeney, there has been a clampdown on the democratic rights of Labour members.

“This has led to a small clique making out-of-touch decisions that have left the Prime Minister and the government deeply unpopular — from the mess over winter fuel payments to the appalling decision to make Peter Mandelson the US ambassador.

“We need an urgent end to this nasty factionalism coming from the top of the party where the views of Labour members and trade unionists are treated with contempt.

“Restoring democracy in the Labour Party is essential if we are to reconnect with voters and prevent the election of a Trump-style Reform government.”

Mr Burgon, who is secretary of the Socialist Campaign Group of MPs, told the Morning Star: “The Labour Party had been engulfed in a crisis over the fallout of Peter Mandelson’s appointment as US ambassador.

“But that terrible decision did not happen in a vacuum. 

“It was the product of a rotten culture of nasty factionalism that has taken hold at the very top of Labour and which we are determined to sweep away.”

The Campaign for Labour Party Democracy, Momentum, the Labour Muslim Network and Labour Assembly Against Austerity have also signed.

A spokeswoman for grassroots group Momentum said: “It’s proven time and again that Labour members are treated with contempt by this current leadership.

“We’re joining trade union leaders, allied organisations and over 25 Labour MPs in calling for the full restoration of members’ rights to help rebuild trust in our party and across the wider electorate.”

Sir Keir has faced a turbulent few weeks in his premiership, with his judgement questioned over the decision to appoint Peter Mandelson ambassador to Washington DC, despite his links with the paedophile Jeffrey Epstein.

The signatories pointed to the candidate selection for the upcoming Gorton and Denton by-election, which Greater Manchester Mayor Andy Burnham was blocked from standing in.

“Denying local members in Gorton and Denton the right to choose their candidate looks like part of a pattern, alongside the widespread barring of hard-working councillors and the withdrawal of the whip from MPs standing up for their constituents,” they said.

A Labour Party spokesperson said: “The Labour Party is proud to be powered by our brilliant party members as we work to bring about the vital change we were elected to deliver.

“Our Labour government is delivering for families across the country, including tackling the cost of living, cutting NHS waiting lists and restoring pride in local communities.”