There are over 25,000 candidates competing for just 5,000 seats - giving voters an "unprecedented" level of choice in one of the most hotly-contested local elections in history.
This spells problems for the political system that go much further than any difficulties likely to be experienced by Sir Keir Starmer's party.
Leading political scientists say council seats could be won on record-low vote shares, with increased fragmentation in the electoral system driven by the loss of support for the two major parties.
"Most electors are facing multiple choices on the ballot paper and a breakdown of traditional party loyalties - all in all, a recipe for highly variable patterns of voting with some candidates elected on extremely low vote shares," said Sky News elections analyst Professor Michael Thrasher.
More councillors are being elected on lower vote shares - for example, one candidate last year won a seat with as little as 15% support. Experts suggest this could undermine the legitimacy of the current electoral system, as councillors are increasingly likely to be elected in areas where only a small number of people voted for them.
"Choice is good for democracy. It gives a fairer representation of what people actually want," said Rob Ford, professor of political science at the University of Manchester.
"But this puts our electoral system for local elections under pressure, because first past the post is not designed for fragmented competition between five strong parties."
This will be the largest set of local council elections under Sir Keir's Labour government, with voters in 136 councils going to the polls across England on 7 May this year.
Analysis by Professor Thrasher, alongside Professor Colin Rallings, suggests both major parties may lose hundreds or even thousands of seats come Thursday, with Labour estimated to lose up to 2,000 and the Conservatives losing 1,000 in the most extreme scenario.
The rise of smaller parties in the polls, in particular Reform UK and the Greens, may be taken as a symptom of the decline of Labour and the Conservatives.
Most of the seats up for grabs were last contested four years ago, with the exception of county council seats which were last contested in 2021.
In 2022, the Conservatives and Labour combined took around 68% of the national equivalent vote (NEV) - the estimated share that parties would have won if local elections were held across the country, as calculated by Professor Thrasher and Professor Rallings.
Now, the two parties' combined share in the polls has nearly halved - sitting at just 36% altogether, according to YouGov - while Reform, the Greens and the Lib Dems have emerged as serious contenders.
Since the first-past-the-post system is not necessarily designed to handle such a variety of parties and candidates, council seats could be won with a smaller and smaller share of the vote.
"These are uncharted waters," said Professor Ford. "Many councillors will be elected with very low vote shares, meaning even amongst the minority of voters who turn out for local elections, a large majority will have backed a different candidate to the winner."
Already, local elections see low turnout, with just one in three voters (34%) turning up to the polls last year. But with an average of nearly five candidates per seat this year, and as many as 22 in a single ward, there is potential for councillors to win with fractional support from their local electorate.
Local by-elections since May 2025 have seen seats won with fragmented support - an average of 41.6% of the vote share, with a new average low of 39% over the course of 2026 alone - analysis by Professor Thrasher and political researcher Hannah Bunting has found.
The lowest winning result in a by-election since last May was in Severn, Gloucestershire, where a Green candidate triumphed with 27.8% of the vote. This figure, combined with low turnout (26.8%), meant that they won with just 7.5% support from the local electorate.
In other areas, seats have been won with margins as low as eight votes.
Today's voters are divided between an increasing number of parties, or not voting at all. Part of this is due to the loss of trust in political systems, with data from the British Social Attitudes Survey showing that an increasing number of people believe we should change our voting systems.
Labour likely to lose seats in left-leaning areas
Last year, Reform dominated in local elections, winning 680 out of 1,641 seats mostly at the expense of the Conservatives.
But this year Labour have the most to lose, as they currently hold more than 2,500 of the council seats up for election.
"Labour is having to defend over half of the 5,000 seats available this year knowing that its performance in council by-elections confirms its dire poll ratings," said Professor Thrasher.
The latest polls from YouGov suggest that Labour has slipped to third place (18%) in terms of national voting intention, even falling behind the Green Party according to some polls over the last three months. And its recent performance in by-elections points to a downward trajectory.
Since last May, Labour has lost control of 44 council seats in by-elections across England - more than any other party. Over half of these were lost to Reform candidates.
That puts Labour's current loss rate at 78.5%, even higher than the 66% of seats they lost at last year's local elections.
Many of the areas taking part in local elections in May this year tend to lean more towards the left of the political spectrum, such as the metropolitan boroughs, with elections in London, Birmingham, Sheffield, and Manchester, to name a few.
This means that we may see more apparent fragmentation on the left than last year, with parties such as the Greens and Jeremy Corbyn's Your Party fishing from the same pool of voters as Labour.
On average, the wards being contested this year are slightly more diverse and less rural than England as a whole.
"Big cities are areas where Labour did well in 2022, but left-wing parties in general are all relatively stronger because of the underlying demographics," said Professor Ford.
"There are more young people in cities, more graduates, more remainers, more ethnic minorities. In particular, these are all groups that do not tend to be very Reform-friendly."
Another key development since the last set of local elections in these areas, in particular for Labour and the left-wing cohort, is the conflict in Gaza, which has followed the Hamas-led attack in southern Israel on October 7 2023.
Sir Keir's stance on the conflict ostracised a portion of the Muslim vote, in part contributing to Labour's poor performance with ethnic minorities in the 2024 general election.
"In many of the areas with big Muslim populations, none of the dissatisfaction over Gaza had yet manifested in local election results when these seats were last contested," explained Professor Ford.
"For example, this year you've got Birmingham, you've got north-east areas of London and many other areas with large Muslim communities. We may see very large swings against Labour, and both the Greens and independents may do well."
The widespread disillusionment with Labour means that the party to watch may be the Greens, who have grown in popularity under the leadership of Zack Polanski and seen an upturn in the polls since their win in the Gorton and Denton by-election.
"The Greens are benefiting from the deeply entrenched unpopularity of the government, particularly with voters who see themselves on the progressive left," said Professor Ford.
"Opposing an ineffective prime minister, who is unpopular with his natural core electorate, is an optimal environment for the Greens."
The London bubble
Some 136 councils across the country will be up for election, but one area will be particularly under the microscope: Greater London.
The capital comprises of 32 London boroughs, covering approximately six million voters. Labour has traditionally dominated London local elections, controlling 21 boroughs, some of which it has held for decades.
But this year's elections may be the real test for Sir Keir's party. If Labour loses control of councils such as Barking & Dagenham, where it previously won 69% of the local vote, or Starmer's own local council of Camden, it could spell trouble for the party in areas of historic support.
"With whole council elections taking place in London and half the metropolitan boroughs, Labour could lose control of authorities it has run for the past 50 years," said Professor Thrasher.
Read more: Where are the elections taking place and when will we find out the results?
Labour may win the highest vote share in just 15 boroughs, a recent MRP poll by YouGov for Sky News estimated. This could take Labour close to its lowest-ever number of London boroughs won in a local election, which stood at 12 in 1982.
For Reform, winning its first council seats in London outside of a by-election will be significant. But taking control of any metropolitan council from Labour could mark a shift in traditional urban politics.
What to look out for on 7 May
Councils are only one part of the local elections taking place across Britain next week - with devolved elections for parliaments in Scotland and Wales, in addition to local mayors in six London areas.
But the scale of these council elections in areas across England means that they may be the best indicator of current party politics, and in particular, Labour's loss of support since coming into government.
Come to Sky News on the night to see live coverage of local election results as they are announced, with detailed analysis of what this may mean for you.
