Labour could see its worst-ever performance in the upcoming local elections, pollsters warned, as some projections see the governing party lose more than 1,000 seats in the crucial contests.

Over 5,000 council seats will be up for grabs when voters in England go to the polls on Thursday, 7 May, in what could prove a decisive battle for Sir Keir Starmer’s leadership.

The prime minister has been grappling with ailing popularity polling for over 12 months – both for himself and his party – as other leadership contenders, such as Andy Burnham or Angela Rayner, could look to capitalise on discontent with the government.

Pollsters have predicted that Labour could see historic lows across local elections for councils, with the Conservatives also expected to struggle.

The biggest winner is forecast to be Nigel Farage’s Reform UK. He will be hoping for a repeat of last year’s local elections, where his party increased its number of council seats by a massive 677.

The Green Party is also projected to see significant gains across the country, galvanised by a swell of popularity following the election of Hannah Spencer to parliament in Gorton and Denton in February.

Speaking to The Independent, the political scientist John Curtice said the elections pose a “remarkable calamity” to the government and the Conservatives.

He said: “2024 posed the question as to where the two-party system would go if indeed the Labour government hit electoral trouble. The way that things have transpired since have reinforced that.

“These elections could well provide a further significant organisational boost to the ability of [Green and Reform]”.

Stephen Fisher, a professor of political sociology at the University of Oxford, has forecast that Labour will lose 1,900 councillors at the upcoming elections, dropping 74 per cent of the seats it is defending.

This would mark the worst local election performance for any prime minister in history. In a clear sign of the rising discontent for Britain’s two largest parties, the Conservatives could also see a net loss of 1,010 councillors, Professor Fisher estimated.

The election expert also found that Reform could gain 2,260 councillors, tripling its local representation in England. Meanwhile, the Greens could gain 450 and the Liberal Democrats 200.

If forecasts are proven correct, the result would be a devastating blow to the premiership of Sir Keir and likely reopen the possibility of a leadership challenge.

The Labour leader has come under renewed pressure in recent weeks over the appointment of Peter Mandelson as US ambassador, virtually erasing the slight uptick in popularity that the government enjoyed over its handling of the US-Iran war.

“Starmer has never been a popular leader,” Sir John said, “he’s never managed to sell himself to the electorate. He’s never been able to define what he is about and where he’s trying to take the country.”

He added that the most popular person to replace Sir Keir is Andy Burnham, currently ranked as the UK’s most popular politician by YouGov. However, the Manchester mayor was blocked from standing in Gorton and Denton by the Labour Party’s governing body.

There have been renewed calls in recent days from across the political spectrum for Sir Keir to resign in the wake of revelations that Lord Mandelson was approved for the role despite failing his vetting process after Foreign Office intervention. Likely, these calls would only grow louder should the party’s local support also collapse on 7 May.

In London, every council seat in all 32 boroughs is up for election. The capital has been seen as a Labour stronghold in recent years, with the party holding majority control in 21 councils.

But the last set of London elections were in 2022, with the political landscape shifting dramatically in the past four years. Sir Keir’s Labour has only declined in popularity since becoming the governing party in 2024, with its handling of issues such as Gaza and migration pushing young, progressive voters away from the party.

This dynamic has benefited the Green Party most of all, with leader Zack Polanski working to position the group as a further left alternative to Labour since taking up the role last year.

The Greens currently hold only 49 councillors in London, although they still make up the second largest party in five boroughs. Recent polling by YouGov suggests this number could skyrocket, with the party projected to take the highest vote share across four councils, including Lewisham and Lambeth.

The same poll found that Reform could take the highest share in three. Neither party has ever previously topped the poll on any council in London.

The last time Labour won fewer than 15 London councils was in 1982, 44 years ago, when they won just 12.

Labour sources told The Independent earlier this week they are expecting a “bloodbath” in Islington, while Green Party sources said they were expecting to take Hackney.

Mr Curtice said: “The Labour vote is going first of all to the Greens; that’s the principal destination now of 2024 Labour voters who defect. And then there’s the Liberal Democrats and Reform. Virtually no one is going to the Tories.”

“Reform are fighting 99.9 per cent of the wards; the Greens are fighting over 90 per cent as well,” he added. “This is a very strong sign.”

Other seats up for grabs are spread across the North, the Midlands and the South. Traditionally, Labour-voting cities like Birmingham, Manchester, Newcastle and Wolverhampton are all holding elections, with discontent with the government making the outcomes less predictable.

Polling from Britain Elects finds that – while all of these are likely to remain under Labour’s control – Reform, followed by the Greens, are set to make a large dent in the party’s seat count.

Mr Farage’s party could also wrest control or take the most seats without a majority in a number of councils outside of the biggest cities, the polling finds. Areas like Wakefield, Sunderland, and Thurrock are all projected to see power switch from Labour to Reform at the upcoming event.

The Greens, meanwhile, have strong prospects in Sheffield, where they are projected to win a minority of seats, and are understood to be concentrating their campaigning efforts in Newcastle.