Since UK Prime Minister Rishi Sunak called a surprise snap general election in a rain-soaked announcement outside 10 Downing Street in late May, the election campaign, which has been littered with political scandals and gaffes, has played out at breakneck speed.

Political analysts and polls suggest a historic election with the main opposition party, Labour, on course to usurp the Conservatives who, after 14 years in power, now face a run-off for the opposition with the right-wing populist Reform UK.

All will be settled on Thursday this week, when British voters head to polling stations nationwide to cast their ballots in the 2024 general election.

Here is what you need to know about election day:

How and when will the UK general election be held?

The 2024 UK general election will be held on Thursday, July 4, between 7am (06:00 GMT) and 10pm (21:00 GMT).

Registered voters in the 650 parliamentary constituencies will vote for their preferred candidate at polling stations set up for the day, usually at schools or community centres.

The UK uses a first-past-the-post (FPTP) system, an old racing metaphor applied to voting in which the candidate with the most votes becomes a member of parliament (MP) for that constituency, irrespective of whether they’ve secured 50 percent of votes cast.

FPTP differs from a proportional representation (PR) system, which most European countries use, and from a system like the one France is using in its election (first round was on June 30; second round will be on July 7), in which constituencies that don’t give a majority of votes to any one candidate go to a second round of voting.

In the PR system, parliamentary seats are allocated in proportion to the number of votes each party receives.

Once the polls close in the UK, the votes will be counted, and the MPs with the most votes in each constituency (each constituency has one seat in Parliament) will be declared winners by the early hours of July 5.

If a party wins a majority of seats – as Labour is expected to – its leader becomes the prime minister, and the leader of the party with the second-highest number of MPs typically becomes the leader of the opposition. Keir Starmer is the leader of the Labour Party, while Sunak is leading the Conservative Party in the election.

If no party achieves a majority, a hung parliament will be announced. If this occurs, the largest party can choose to form a coalition with other parties.

Why did Rishi Sunak call the elections for July 4?

General elections in the UK must be held no more than five years apart.

The last general election was held in December 2019, which meant PM Sunak had until December to call an election.

The prime minister took the nation by surprise when, on May 22, he called a snap election.

It’s a decision that John Curtice, professor of politics at the University of Strathclyde, says remains an “utter mystery” to anyone outside Sunak’s inner circle.

Curtice said various “speculative theories” are floating around, including the idea that the Conservatives may have felt the economic forecast would not improve before the end of the year.

Another possibility was that the ruling Conservative Party was not convinced they would stem the record number of asylum seekers from crossing the English Channel that separates southern England from northern France.

The Conservatives have made several pledges to halt irregular migration across, including a highly controversial plan to send some asylum seekers to Rwanda.

Why are the Conservatives performing so badly in the polls?

Since 2019, when the Conservatives won the last general election with a large majority, the party has struggled with issues of “trust and competence”, Jonathan Tonge, professor of politics at the University of Liverpool, told Al Jazeera.

A scandal dating back to the COVID-19 pandemic, known as “partygate“, affected the public’s trust in the government and led Boris Johnson to resign as prime minister in 2022.

Johnson was accused of holding a birthday party and other events that breached the strict lockdown rules he had imposed on the British public.

He was replaced by Liz Truss, who oversaw a chaotic six-week tenure that sent markets into freefall.

Tonge said that at this point, Conservatives “lost the trust of the British public”, with Boris Johnson going from a “popular figure to one who was seen as untrustworthy” and Labour overtaking the governing party in poll ratings soon after.

Recently, another scandal struck when the UK Gambling Commission announced it was investigating individuals linked to the party, including two Conservative candidates, Craig Williams and Laura Saunders, for betting on a July election three days before Sunak announced the date. The party subsequently dropped both Williams and Saunders from its list of candidates.

Tonge said the competency issue is due to the Conservatives’ perceived lack of “real improvements” for the British public over the past 14 years.

He said that they have performed well by some measures, with inflation down again and unemployment consistently low.

However, on social aspects, which include “big increases in waiting lists for the National Health Service and a failure to deliver on key policies such as curbing immigration, the Conservatives seem to have failed to deliver on what they promised”.

What is the political party Reform UK, and what are its chances?

Reform UK, led by the populist figurehead, Nigel Farage, stood in the 2019 general elections as the Brexit Party but did not contest Conservative-held constituencies.

Then, it failed to win any seats but, according to the latest polls, this year the rebranded party is challenging the Conservatives for second place.

Farage’s firebrand campaign, which has seen a wave of jingoistic rhetoric focused on immigration, has greatly contributed to their rise.

Curtis said Farage has come across as “charismatic and articulate”, attributes that starkly contrast to Sunak’s campaign, which includes a gaffe in which he left the 80th anniversary of the Normandy landings early.

Curtis said that by focusing on immigration reform, the UK did not target an issue that was particularly crucial to why people were defecting from the Conservatives, but they were “advertising policy failure”.

“If you’re unhappy with the government and you are in the pro-Brexit, anti-immigration camp, Reform UK is where you go,” he said.

What is the most likely outcome?

According to the latest polls, Labour is the clear favourite to win a majority.

Curtis said the polls suggest record lows for the Conservatives, who face a very difficult “arithmetical reality” since their voters fall most heavily in constituencies they are trying to defend. Yet, unlike in 2019, Reform UK will challenge them in those areas.

Tonge said he expects turnout to be slightly down from the last election – estimated to be 67.3 percent – when the country was gripped by a national “fervour” about how the UK should deliver on the vote of the 2016 Brexit referendum.

Voter engagement, he said, does not appear to be as strong this election cycle, and evidence suggests a degree of voter disillusionment with the two main parties, Labour and the Conservatives, that have traditionally dominated UK politics.

He said Labour’s rise can be attributed more to a “Conservative implosion” than any popular policy.

Tonge predicted an “apathetic landslide” for Labour, which could result in a slightly lower turnout than the last election.

Based on current forecasts, he said that getting more than 100 seats would be a good result for the Conservatives in this election. This would mark a huge drop from the 2019 general election when they won 365 seats.

Tonge said such a result would provoke an “ideological and political debate for the heart and soul of the British political right”. The Conservatives would be left with a choice of going down the “Farage route” – going tougher on immigration and tax cuts – or having nothing to do with Reform UK and trying to rebuild as a centre-right party.