Next United Kingdom general election

Electoral system

Each parliamentary constituency of the United Kingdom elects one MP to the House of Commons using the "first past the post" system. If one party obtains a majority of seats, then that party is entitled to form the Government, with its leader as Prime Minister. If the election results in no single party having a majority, then there is a hung parliament. In this case, the options for forming the Government are either a minority government or a coalition government.

The postponed Sixth Periodic Review of Westminster constituencies, reducing the number of constituencies from 650 to 600, is due to report in time for the 2020 election. In 2016 each of the four parliamentary Boundary Commissions of the United Kingdom recommenced the review process.

Date of the election

The Fixed-term Parliaments Act 2011 introduced fixed-term Parliaments to the UK, with elections scheduled every five years following from the 2015 election on 7 May 2015. This removed the power of the monarch, acting on the advice of the Prime Minister, to dissolve Parliament before its five-year maximum length, except in specific circumstances. The Act permits early dissolution if the House of Commons votes by a supermajority of two-thirds. A government can still lose a vote of no confidence by a majority of just over 50%, requiring it to resign. Parliament is then dissolved if no new government can be formed within 14 days of a no-confidence vote.

Should these circumstances not occur, the election is due to take place on 7 May 2020. Under Section 14 of the Electoral Registration and Administration Act 2013, the current Parliament will be dissolved 25 working days before this, so that, assuming that Good Friday, Easter Monday and the first Monday in May are UK public holidays in 2020 (as they have been for many years), the date of dissolution will be Monday 30 March 2020. The Prime Minister has the power, by order made by Statutory Instrument under section 1(5) of the Fixed-term Parliaments Act 2011, to provide that the polling day is to be held up to two months later than 7 May 2020. Such a Statutory Instrument must be approved by each House of Parliament. Furthermore, individual constituencies may be forced to delay their elections. In both the 2005 and 2010 general elections, one constituency delayed its poll due to the death of a candidate.

The referendum on EU membership resulted in a majority vote to leave the European Union; initial reactions to the result caused the pound sterling to fall in global markets. Many political commentators argued that it might be necessary to hold an early general election before negotiations to leave begin; for example, Conservative MP Jacob Rees-Mogg suggested that a general election could be held in autumn 2016. The Conservative Party leadership election triggered by David Cameron's resignation perforce also chose a new Prime Minister. The leading candidates in that election ruled out an early election, but after Leadsom's withdrawal and Theresa May thus due to become Prime Minister without any broader vote, there were renewed calls for an early election from political commentators, as well as Tim Farron, leader of the Liberal Democrats.

Contesting political parties and candidates

Most candidates are representatives of a political party, which must be registered with the Electoral Commission's Register of Political Parties. Candidates who do not belong to a registered party can use an "independent" label, or no label at all.

The Conservative Party and Labour Party have been the two biggest parties since 1922, and have supplied all UK Prime Ministers since 1935. Both parties will enter the election with different leaders from the 2015 election. David Cameron, who has been leader of the Conservative Party since 2005 and Prime Minister since 2010, announced in March 2015 that he would stand down as Conservative Party leader at some point before the end of the 56th Parliament. On 24 June 2016, following the referendum on the UK's membership of the European Union, Cameron announced that he would step down by the date of the Conservative Party's conference in October. He did in fact step down as Prime Minister on 13 July 2016, and was replaced by the former Home Secretary Theresa May. The Labour Party, who are the Official Opposition party, conducted a leadership election following the resignation of Ed Miliband in the aftermath of the 2015 election. Jeremy Corbyn was announced as the new leader in September 2015. However, following losses of council seats in the 2016 local elections (the first time the Official Opposition had done so in a non-General Election year since 1985) and a perceived lacklustre campaign in the EU referendum he has come under increasing pressure, with 21 out of 27 of his shadow cabinet resigning or refusing to attend, and the Parliamentary Labour Party passing a motion of no confidence in him by 172 to 40. Despite being forced to appoint people to multiple shadow cabinet positions, Corbyn refused to resign. A second leadership election was held, in which Corbyn won with an increased majority, defeating rival Pontypridd MP Owen Smith. Following Conservative's win in the Copeland by-election on 23 February 2017, the first time the governing party gained a seat in a by-election since 1982, as well as the first time the constiuency had elected a Tory since its creation in 1935, additional calls for Corbyn to stand down as leader came.

While the Liberal Democrats and their predecessors had long been the "third party" in British politics, they lost 49 MPs in the 2015 election, with many fewer MPs than the Scottish National Party (SNP) and many fewer votes than the UK Independence Party (UKIP). Tim Farron became the Liberal Democrat leader in July 2015 following the resignation of Nick Clegg, with an aim of rebuilding the party's representation. The SNP, led by First Minister of Scotland Nicola Sturgeon, stand only in Scotland, but won 56 of 59 Scottish seats in 2015, an increase of 50 MPs. UKIP, led by Nigel Farage, won 12.7% of the vote in 2015 but only gained one MP. UKIP was founded with the UK's departure from the EU as a constitutional aim, and their role at the next general election will be influenced by the Leave result of the referendum on the UK's membership of the EU on 23 June 2016, and subsequent events. The Green Party and Plaid Cymru were the other parties in Great Britain to return MPs at the 2015 general election, and are also likely to contest the next election, along with hundreds of minor parties.

Politics in Northern Ireland is largely separate from the rest of the UK. All Northern Irish parties who returned MPs at the 2015 general election (Democratic Unionist Party (8); Sinn Féin (4); Social Democratic and Labour Party (3); Ulster Unionist Party (2) will likely contest the next election. Sinn Féin is likely to continue its policy of abstentionism and not take any seats won at the next general election.

Conservative

1. Sir Simon Burns (Chelmsford), announced 8 January 2016
2. Kenneth Clarke (Rushcliffe), announced 6 February 2016
3. Sir Oliver Letwin (West Dorset), announced 19 July 2016

Labour

1. Ronnie Campbell (Blyth Valley), announced 8 May 2015
2. Pat Glass (North West Durham), announced 28 June 2016
3. Jim Fitzpatrick (Poplar and Limehouse), announced 13 September 2016

Inaccurate polling at the 2015 election

At the 2015 election, all major opinion polls failed to predict the election result accurately. All pollsters had forecasted a hung Parliament, underestimating the Conservative Party vote by an average of 4.2 points and overestimating the Labour Party vote by an average of 2.4 points. Almost immediately following the election polling companies started making changes to polling practices, with recommendations from a review by the British Polling Council likely to see further alterations.