Voters in England, Scotland and Wales will go to the polls today to elect councillors and - in eight areas - mayors.
With a snap general election just five weeks away, commentators will use these council elections as an early indicator for what might happen on June 8.
Unlike in a general election, however, most of the results won't be announced in the dead of night, so there's no need to stay up in order to watch the action unfold. Here we assess the main parties' chances in England, Scotland and Wales and highlight the key councils to look out for as well as what it could all mean for the general election.
What to watch out for in England?
The English elections will see 2,370 seats contested in 27 county councils, seven English unitary authorities and one metropolitan authority.
Under usual circumstances local council elections are something of an open goal for whoever is in opposition, with voters taking advantage of the opportunity to give the Government a kicking.
However, these are not normal times. Jeremy Corbyn has alienated a large portion of former Labour voters and – while the majority of councils up for grabs in England are Conservative strongholds – all the signs point to Tory gains rather than losses.
Labour only completely controls four of the 35 councils up for election on May 4 – Durham, Derbyshire, Doncaster and Nottinghamshire – but it also has minority control in Northumberland and is the major coalition partner in Lancashire and Cumbria.
Of these councils, Labour only has a strong foothold in Durham and Doncaster. Given their performance in the Copeland by-election, the rest of Cumbria may well follow suit by favouring the Conservatives, while Labour lead the Tories by just four seats in Lancashire.
If Labour loses control of its Midlands councils of Nottinghamshire and Derbyshire it may well spell doom for the party in these areas in the forthcoming general election. These areas voted heavily to Leave the EU last June and will provide an indication as to which way Labour's Brexit heartlands will lean on June 8.
English councils to watch:
- Cumbria - result expected 8am, Friday
- Derbyshire and Lancashire - results expected 4pm, Friday
- Nottinghamshire - result expected 5pm, Friday
- Cornwall - result expected 3pm, Friday
Labour could become Scotland's third party
Scotland was the scene of a spectacular collapse in Labour support at the 2015 general election with Ed Miliband's party losing 40 seats to the SNP.
A similar bloodbath looks likely on May 4 when all 1,223 Scottish council seats are up for election.
Labour support has fallen even further north of the border under Jeremy Corbyn, with recent polls showing that the party could slump to third place, behind the Conservatives, when it comes to vote share in council elections.
In 2012 – the last time Scottish councils were elected – Labour attracted 31.4 per cent of the vote, slightly behind the SNP on 32.2 per cent but well clear of the Conservatives, on 13.3 per cent.
However, polling by Ipsos Mori and STV in March showed that only 17 per cent of Scots were intending to vote Labour this time around, less than the 19 per cent who said they'd vote Conservative. The SNP would be well ahead of both on 46 per cent.
If this were to be the final result it would be a historic low for Labour in Scotland and could well mean they lose a significant number of the 374 council seats they currently hold.
While Labour only controls five councils in Scotland outright, they have minority control or a place in a ruling coalition in a further 14 council areas. This effectively puts them in at least joint control of around half the country.
However, this gives them a fragile grip on power, one that could be broken by even small swings away from the party.
Glasgow City Council looks particularly vulnerable for Labour. Their lead over the SNP here is just 12 seats and, given the huge swing the SNP enjoyed in the city in the 2015 general election, this could be easily wiped out.
If the Conservatives also gain ground in Scotland - as local and general election polling suggests they will - then Labour could be squeezed out of a country that was formerly a safe bet for them both in the local and general elections.
Scottish councils to watch:
- Aberdeen - result expected 3pm, Friday
- Glasgow - result expected 4pm, Friday
- Edinburgh - result expected 5pm, Friday
Wales is theoretically a more secure area for Labour
Labour are more secure in Wales by virtue of the fact that they hold large majorities in the areas where they are in control.
They have their slenderest lead in Merthyr Tydfil, but given that the Labour majority here is still as many as 17 seats there is little prospect of this switching hands.
In last year's Welsh Assembly elections Labour's share of the vote was 34.7 per cent, down from 42.3 per cent in 2011. However, due to the distribution of voters they only lost one seat. There's a strong prospect we'll see something similar happening in the upcoming council elections.
Recent polls for the general election have show the Tories doing much better in Wales. If this is to play out in today's voting then they could seize full control in Monmouthshire and threaten Labour in Newport and the Vale of Glamorgan.
If the Conservatives manage to put in a strong performance in these areas then it could pave the way for a strong outing at the general election on June 8.
Welsh councils to watch:
- Newport - result expected 4am, Friday
- Monmouthshire - result expected 5am, Friday
- Vale of Glamorgan - result expected 7am, Friday
The Brexit effect
These local elections are likely to be a test of just how Brexit will effect Labour. There are 38 councils up for election across England, Scotland and Wales in which Labour is the largest party. Of this number half had majorities in favour of Leave in last June's referendum - some with vote shares of more than 60 percent.
Theresa May's dedication to a hard Brexit has proved appealing to voters in recent polls and this could eat into Ukip's votes as well as Labour's.
Meanwhile the Lib Dems continuing to make a comeback as the only big anti-Brexit voice.
With success in several council by-elections, as well as in the constituency by-election for Richmond Park, Tim Farron's party will hope to show further signs of growth after their decimation in the 2015 general election.
Some polling forecasts see the Lib Dems gaining around 100 seats in the council elections. This could mean that they will assert full control of Cornwall Council. Cumbria and Somerset will also be in their sights.
In all of these cases they local elections will provide a glimpse as to the effect that Brexit might have in the general election next month.
The council elections aren't the only show in town with elections for eight mayoral positions up for grabs in England as well.
The mayoral elections - such as those for the new "metro mayors" in Manchester and Liverpool - are likely to give Labour something to cheer about as they are taking place in the party's heartlands.
Just as with Sadiq Khan's London mayoral win, expect to hear Jeremy Corbyn claim victories in Manchester and Liverpool as signs of strong Labour performance under his watch.
Labour have three former and current Labour MPs standing in urban strongholds: Andy Burnham in Manchester, Steve Rotheram in Liverpool, and Siôn Simon in the West Midlands.
However, the Tories are hoping for success in the West Midlands with Andy Street, former managing director of John Lewis. If this happens then Labour's hopes of a strong performance in the Midlands next month may well take a beating.