Most of the country will vote on Thursday to elect mayors and thousands of councillors in some 200 different council areas.
For Boris Johnson, it will be seen by some in his party as a referendum on his leadership, while Labour leader Sir Keir Starmer will hope for signs the red wall is coming back.
In Scotland, it will be regarded as a verdict on the First Minister Nicola Sturgeon, in particular her handling of the Covid pandemic.
But what are the regions to watch, what will happen and when will we know?
What are the key battlegrounds?
Scotland is unique for the UK, in that not one mainland council has a party with absolute control.
Of the country’s 32 authorities, just three have a majority – Orkney, Shetland and Comhairle nan Eilean Siar and all are run by independents.
This means despite the SNP going into the election with the most seats, they will need to make gains to run councils entirely.
One key area is Dundee, where they control their highest proportion of councillors and need just two more councillors to retake it.
Another big goal for Ms Sturgeon’s party will be Renfrewshire and Clackmannanshire, which they can take control off with just a few more seats.
However, East Renfrewshire Council will be no easy thing, representing a three-way battle between the Conservatives, Labour and the SNP.
Another key battleground is Aberdeenshire, which while a Conservative stronghold has power shared between several parties.
It is run by the Tories with the Lib Dems and a group of independents, and will be one to watch to see how Douglas Ross’s leadership is perceived.
Another crucial area will be Glasgow, where the SNP is hoping to take complete control of the city for the first time ever.
Currently holding 35 of the 85 seats, the party’s own polling suggests its possible, but those in Labour are quietly hoping to take more of the city back.
Edinburgh is also a key fight, with no-one standing enough candidates to win a majority.
The city council has been run by a joint SNP-Labour administration for the past five years, but will be a potential four-way fight, with SNP and Tories likely the biggest parties.
South of the border, Wandsworth is one of the councils to watch. Tory since 1978, it has seen council tax cuts and rents frozen on council homes.
Despite this, it is one of Labour's key London targets, and with a majority of just three, a few hundred votes could swing it in a coup for Sir Keir.
Labour-run Bury is also a huge battleground, with both Sir Keir and Mr Johnson visiting during the campaign.
Other southern councils where the Conservatives are expected to face a challenge include Barnet, Harlow, and Southampton.
What is likely to happen?
As the polls have shown us repeatedly, they are not always helpful and never to be taken as gospel, but instead an indicator.
In the last set of local elections in May 2021, the Conservative Party made a net gain of 235 council seats and took control of 13 councils.
However, things are far more precarious for the Tories this time around, with the party struggling to address the rising cost of living and the ongoing Partygate saga.
As a result, Conservatives have been briefing they could face catastrophic losses, something they know is simply not going to happen.
This is expectation management, so the few losses they do face look like a failure for a Labour leader who seems to be taking “beergate” in his stride.
While Sir Keir’s party have led in consecutive polls, anything more than a three-point swing and a few gains from the Tories to his party and the Lib Dems would be a surprise.
Not all of England is voting, and out of London and the cities the Tory vote feels far safer.
Even outside London, Labour currently control almost as many of 114 councils at stake as the Conservatives, and will be defending nearly 1,100 seats to the Conservatives’ 900.
As a result, this will not be the huge night for Labour to show they can win the red wall back or are ready for government.
Simply put, there are not enough seats up for grabs for Labour to hurt the Tories enough to feel significant.
It is in Scotland where Mr Johnson faces his biggest challenge, with all 1,226 seats on the country’s 32 councils are at stake.
The last locals were held in 2017, when the Tories were high in the polls, giving the Scottish Tories their best local election result since 1982.
With much lower polling and a more toxic Prime Minister, they are likely to be supplanted by Labour in the battle for second place.
For the SNP, the party can expect to grow its support, but is unlikely to sweep the board.
When will we know who has won and what happens after the election?
Polls will close at 10pm today, and then the votes start to be counted.
Local councillors who are elected will then hold the role for four-year terms.
They will be responsible for a wide range of issues from transport, rubbish collection, planning applications, and managing mental health services.
The results are expected in the early hours and throughout the day on Friday, with some councils also likely to declare as late as Saturday.
Vote counts in Scotland and Wales will not begin until Friday, with the earliest results not expected until that afternoon.
In England the counts start overnight in around half of the councils, with the rest starting Friday.
The results should be a bit clearer by Friday evening, with all results in by Sunday.