Withdrawal of the United Kingdom from the European Union In July 2016, Theresa May was elected Prime Minister to succeed David Cameron, who had resigned following the 2016 Brexit referendum.

In the face of opposition from the DUP and Conservative backbenchers, the second May ministry was unable to pass its Brexit withdrawal agreement by 29 March 2019, so some political commentators considered that an early general election was likely.

[47][48] United Kingdom invocation of Article 50 of the Treaty on European Union came in March 2017, and Theresa May triggered a snap election in 2017, in order to demonstrate support for her planned negotiation of Brexit.

[65] The Liberal Democrats originally pledged that if they formed a majority government, which was considered a highly unlikely outcome by observers,[66] they would revoke the Article 50 notification immediately and cancel Brexit.

[69] The Democratic Unionist Party was in favour of a withdrawal agreement in principle but opposed the deals negotiated by both May and Johnson, believing that they created too great a divide between Northern Ireland and the rest of the United Kingdom.

[79] The Institute of Fiscal Studies (IFS), an influential research body, released on 28 November its in-depth analysis of the manifestos of the three main national political parties.

[85] The IFS highlighted a raft of changes in including free childcare, university, personal care, and prescriptions, as well as nationalisations, labour market regulations, increases in the minimum wage, and enforcing "effective ownership of 10% of large companies from current owners to a combination of employees and government".

The IFS said that Labour's vision "is of a state not so dissimilar to those seen in many other successful Western European economies", and presumed that the manifesto should be seen as "a long-term prospectus for change rather than a realistic deliverable plan for a five-year parliament".

[81] The Conservative manifesto was criticised for a commitment not to raise rates of income tax, National Insurance, or VAT, as this put a significant constraint on reactions to events that might affect government finances.

Other policies included increased spending on the NHS; free childcare for two-to-four-year-olds; recruiting 20,000 more teachers; generating 80% of electricity from renewable sources by 2030; freezing train fares; and legalising cannabis.

[72] Under the first-past-the-post electoral system, there is often concern, especially in marginal seats, that if voters of similar ideological leanings are split between multiple different parties they may allow a victory for a candidate with significantly different views.

[124] Senior opposition politicians from Labour, the Liberal Democrats, and the SNP launched a late-stage appeal to anti-Conservative voters to consider switching allegiance in the general election, amid signs that tactical voting in a relatively small number of marginal seats could deprive Johnson of a majority in parliament.

[129] At the start of the election period, Labour-supporting organisation Momentum held what was described as "the largest mobilising call in UK history", involving more than 2,000 canvassers.

[130] The Liberal Democrats were considered possible winners of a number of Conservative-held southern English constituencies; a large swing was postulated that might even topple Dominic Raab in Esher and Walton.

[131] At the beginning of the 2019 campaign, they had been accused of attempting to mislead voters by using selective opinion polling data,[132] and use of a quotation attributed to The Guardian rather than to their leader Jo Swinson.

[134] The Liberal Democrats won a court case stopping the SNP from distributing a "potentially defamatory" leaflet in Swinson's constituency over false claims about funding she had received.

In the first week of November, Labour was reported to have four of the five most liked tweets by political parties, many of the top interactions of Facebook posts, as well as doing very well on Instagram, where younger voters are particularly active.

[143] Prior to the campaign, the Conservatives contracted New Zealand marketing agency Topham Guerin, which had been credited with helping Australia's Liberal–National Coalition unexpectedly win the 2019 Australian federal election.

[146] During the 19 November debate between Johnson and Corbyn hosted by ITV, the press office of the Conservative Campaign Headquarters (CCHQ) re-branded their Twitter account (@CCHQPress) as factcheckUK (with "from CCHQ" in small text appearing underneath the logo in the account's banner image), which critics suggested could be mistaken for that of an independent fact-checking body, and published posts supporting the Conservative's position.

[150][151][152] In defence, Conservative chairman Cleverly stated: "The Twitter handle of the CCHQ press office remained CCHQPress, so it's clear the nature of the site", and as "calling out when the Labour Party put what they know to be complete fabrications in the public domain.

[225] In February 2021, an investigation by openDemocracy found that third-party campaign groups "pushed anti-Labour attack ads to millions of voters ahead of the 2019 general election spent more than £700,000 without declaring any individual donation".

[229] Adam Ramsay, who wrote the article, contacted Powers and got her to admit to being an associate at the trade consultancy firm Competere, which was set up by lobbyist Shanker Singham, who works for the neoliberal think tank, the Institute for Economic Affairs.

[226] Following these reports, former Liberal Democrats MP Tom Brake, who lost his seat in the election and was now director of the pressure group Unlock Democracy, wrote to the Electoral Commission, urging them to investigate.

Leaders of the Church of England stated people had a "democratic duty to vote", that they should "leave their echo chambers", and "issues need to be debated respectfully, and without resorting to personal abuse".

Jeremy Corbyn was very unpopular among the Hindus due to his anti-Indian sentiments & his past disparaging comments on the caste system,[250] with many of the community seeing him to be under the influence of Pakistani Muslims,[251] with whom he shared a common pro-Palestinian stance.

[256] Writing in the British Journalism Review, James Hanning said that, when reporting and commenting on Johnson, Conservative supporting newspapers made little mention of "a track record that would have sunk any other politician".

[143] Of the 20 most prominent spokespeople in media coverage of the first week of the election period, five were women, with Nicola Sturgeon, the SNP leader and first minister of Scotland, in seventh place, the most featured.

as of 11 December 2019 An exit poll conducted by Ipsos MORI for the BBC, ITV, and Sky News was published at the end of voting at 10 pm, predicting the number of seats for each party.

In contrast to previous elections, the YouGov survey additionally found that a plurality of voters in the DE's NRS social grade — comprising the unemployed, state pensioners, and semi-skilled and unskilled workers — had opted for the Conservatives over Labour.

[314][315] In a post-election review featuring Labour MPs, trade union officials and activists one of several reasons attributed to the electoral defeat was due to the declining popularity of Jeremy Corbyn in relation to the Brexit position and allegations of party antisemitism.