Major elections will take place across England, Scotland, Wales, and Northern Ireland on Thursday May 5. They will provide the first real barometer of public opinion since the Conservatives returned to parliament with a majority government at the 2015 general election.
Polling stations across the country will be open between 7 a.m. and 10 p.m. on Thursday, with results expected the following morning.
The London mayoral Assembly elections
The capital will elect a new mayor on Thursday with Labour candidate Sadiq Khan favourite to see off rival Zac Goldsmith and replace the outgoing Boris Johnson. The campaign between the pair has been unsavoury in recent weeks, with Tory Goldsmith accused by people like Labour MP Yvette Cooper of Islamophobia for suggesting Khan has given "cover" to religious extremists.
There's also 25 seats on the London Assembly being contested - 11 representing the whole city and 14 constituencies. The current body is made up of 12 Labour members, nine Conservative, two Green party, and two Liberal Democrats. It is the job of Assembly members to hold the mayor to account.
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Sadiq Khan enjoyed eight and ten point leads over Goldsmith in polls published by ComRes and Opinium last month.
English local government and other mayoral elections
2,743 seats will be up for grabs in elections across 124 English councils. They'll provide a true test of Jeremy Corbyn's leadership of the Labour party - with some polling experts predicting the party could potentially lose up to 170 seats nationwide. These seats were last contested in 2012 and saw Labour make gains of over 500 councillors under the leadership of Ed Miliband.
Mayoral elections will also be held in Liverpool and Salford where Labour men Joe Anderson and Ian Stewart currently hold the positions, and Bristol, where incumbent Liberal Democrat George Ferguson will be hoping to return to office.
Scottish parliament
Scotland uses a proportional voting system to elect 129 members (MSPs) to its parliament. Each of the country's 73 constituencies will elect one MSP, while eight larger regions will elect seven each. The Scottish National Party - led by Nicola Sturgeon - is expected to enjoy a comfortable victory. The party won 69 seats in 2011 election and was leading a Survation poll published on Tuesday with a resounding 43%.
The biggest talking point in Scotland will be the battle between Kezia Dugdale's Labour and Ruth Davidson's Conservatives to become the SNP's official opposition. A Panelbase survey published at the weekend gave Labour a six point lead over the Tories. Labour's Scottish presence was effectively wiped out by the SNP in the 2015 general election, and pressure is on Dugdale to steer the party to a second place finish at the very least.
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SNP leader Nicola Sturgeon.
Northern Ireland assembly
The Northern Ireland assembly is made up of 108 members (MLAs) - six MLAs for each of the 18 constituencies. The last election was held in 2011 and saw the right-wing Democratic Unionist Party (DUP) win the most seats (38), and republicans Sinn Féin elected as the second largest party (29). No dramatic changes are expected, but there are concerns about low interest in Northern Irish
BI will be providing minute by minute coverage of the elections.