Some 49 million voters are set to cast their votes on Thursday in what could be described as one of the most crucial polls in a generation.

The election called by the Conservative government in September will be the third parliamentary election in four years and the fourth poll in the same period of time if the 2016 EU referendum is counted.

The polls opened at 7 a.m. local time (0700GMT) and will close at 10 p.m. (2200GMT). Exit polls can be expected as soon as the polling ends, but the final result could be declared as late as Friday evening.

The number of candidates who will compete for the House of Commons seats in 650 constituencies is 3,222.

The poll is the second election called by a Tory premier to secure a working majority in parliament. The first such election, called by then-Prime Minister Theresa May to get a larger majority, cost her the party’s working majority in the House, forcing her to resort to a deal with Northern Ireland’s biggest party, the Democratic Unionist Party (DUP).

To form a government, 326 seats in the parliament are needed. The latest opinion polls suggest the Conservatives would win 339 seats with 43% of the votes, but those who think a new hung parliament will succeed the previous one say past polls did not accurately reflect voting tendencies.

There are more than 3 million newly registered voters who will go to the polls today. Two-thirds of those are under 35, and one-third are under 25. Younger voters are expected to make an impact on the election outcome.

The main threat for the Conservative Party is rising Labour Party votes. Party leader Jeremy Corbyn increased Labour's vote share more than any of the party's leaders since 1945 based on data from the 2017 election. However, opinion polls ahead of Thursday put him at 34% support.

The Liberal Democrats (Lib Dems) are projected to get 12-13% of the vote, while the Brexit Party and Scottish National Party (SNP) are thought to be getting 4% each.

Election promises

Brexit, the National Health Service (NHS), crime, economy, and immigration are the main issues parties focused on during their campaigns.

The Conservative Party based their election campaign on Brexit, pledging to leave the EU on Jan. 31, the deadline granted by the bloc last September. Brexit is the main issue Boris Johnson would like to leave behind by legislating his revised withdrawal agreement through parliament, and it is the reason why he triggered the snap poll in the first place.

The main opposition Labour Party has pledged a new withdrawal agreement with the EU and a confirmatory referendum on the deal.

Liberal Democrats and the SNP have promised to revoke the calling of the Article 50 divorce clause and cancel Brexit, while the Brexit Party has vowed to leave the bloc without an agreement.

Up to 2 million Muslim voters will impact the results in 31 constituencies where the winning candidates' majorities were low in 2017.

Muslim voters could also change the result in 26 other constituencies, while Muslim groups urge voters to decide who to vote for by keeping in mind parties' policies on Islamophobia. This will be a factor against the Conservatives, who have failed to launch an investigation into such problems within their own party.

According to the "first-past-the-post" system in the U.K., the candidate who receives the highest number of votes in any of the 650 constituencies wins the election.

The traditional Queen’s Speech is planned for Dec. 19, but this date needs clarification based on the final election results.

The election results will produce new scenarios:

- Any party winning 326 or more seats can form the new government on its own.

- If Conservatives win the most seats but cannot reach 326 seats, they will look for support for a minority government. However, none of the parties are likely to give them that support. The previous government formed by Theresa May had a “supply and confidence” deal with the DUP to reach a working majority with their 10 MPs in Westminster.

However, the DUP now thinks Johnson betrayed them by introducing a customs border between Northern Ireland and the rest of the U.K. in his revised Brexit deal. Their support, such as any other smaller parties’, is unlikely.

- If Labour wins the most seats in a less likely outcome but gets less than 326 seats, they will try to form a coalition government with one or more parties including the Lib Dems and the SNP to find a working majority in the House. The Lib Dems have said they would not be in a coalition with the Labour Party led by Jeremy Corbyn.

- It is unlikely that any other party wins the most seats and forms a government.