Britain is on the cusp of a new era. Here’s what you need to know about its upcoming general election

Voters in Britain are primed to end a 14-year era of Conservative rule, in a momentous general election that Prime Minister Rishi Sunak is almost universally expected to lose.

Sunak took the biggest gamble of his troubled premiership by calling the early vote, but he has struggled to turn around dire polling and appears on the cusp of defeat.

If, as current polls indicate, the opposition Labour party triumph, it will finally bring down the curtain of a 14-year era of Conservative rule, ushering in a center-left government led by former barrister Keir Starmer.

Any other outcome would mean Sunak has orchestrated a shocking victory that even many in his own party believe is beyond reach – and would result in the Conservatives extending a political dynasty towards a third decade.

Here are some key questions answered.

When and how is Britain voting?

After a weeks-long campaign, polls will open at 7 a.m. local time on Thursday (2 a.m. ET), and they’ll stay open until 10 p.m.

Britons can cast a ballot in each of the country’s 650 constituencies, selecting the MP to represent the area.

The leader of the party that wins a majority of those constituencies becomes prime minister, and can form a government. That means 326 is the magic number for an overall majority.

If there’s no majority, they need to look for help elsewhere, ruling as a minority government – as Theresa May did after a close 2017 result – or forming a coalition, as David Cameron did after 2010.

The monarch has an important, albeit symbolic, role; King Charles III must approve the formation of a government, the decision to hold an election and the dissolution of parliament. The King won’t ever contradict his prime minister or overrule the results of an election.

Why did Sunak call an election?

Sunak was required to call a vote by January 2025, but the decision of when to do so was his alone.

His problem was that no good options existed. He was 20 points behind in the polls, and that deficit hadn’t budged for months. Some in his ear urged him to wait until later in the year, when poor economic news could improve.

But on the other hand, Sunak has placed much of his political capital into his pledge to stop small boat crossings to the UK by asylum seekers. He has recently passed a controversial law to process some claims in Rwanda, though nobody has yet been deported and further legal challenges may await the plan.

The warmer summer months are expected to see a huge number of such journeys across the English Channel, hurting a major pillar of his campaign message.

Ultimately, hours after some rare good economic news – a healthy month-on-month reduction in the rate of inflation – Sunak decided that this was the least bad time to pull the trigger.

But his speech, which took place in a downpour outside Downing Street, set the tone for a miserable campaign.

Who’s expected to win?

The near-universal expectation is that Sunak’s Conservative Party will lose the election.

Labour have been leading in general election opinion polls since late 2021, and that lead has been huge throughout the campaign. They are around 20 points up on average, with the Tories closer to third party challengers Reform UK and the Liberal Democrats than they are to Labour.

When converted to a projection of seats in parliament, those figures indicate either a comfortable Labour win or a Labour win so huge it would spell a near-wipeout for the Conservatives.

The Conservative brand was damaged by Partygate and a number of other scandals that led to the demise of Boris Johnson’s premiership, and then the shambolic six-week tenure of his successor Liz Truss, whose fiscal agenda sent markets into turmoil.

Sunak’s campaign has even shifted its message in recent weeks, encouraging supporters instead to prevent a massive Labour majority than to send Sunak back to Downing Street.

It’s essentially an admission of defeat, and underlines what polling has said for some time: Labour is firmly on course for victory.

But the Labour party is concerned about people taking the result for granted, and have stressed in recent days that nothing is decided until the votes are counted.

How has the campaign gone?

Starmer and Sunak have faced off in two head-to-head TV debates, which were at times ill-tempered and featured contentious claims – particularly an assertion by Sunak that Labour would cost Britons thousands in new taxes, which Labour have ruled out.

Labour’s campaign has been otherwise focused, hammering home a promise of “change” while pledging prudence with the nation’s finances.

Sunak has meanwhile struggled to stay on track; in particular a decision to leave D-Day anniversary commemorations early caused fury back home and prompted an apology.

Two head-to-head TV debates have been organized; in the first, Sunak and Starmer scrapped in a tense and occasionally personal tie. The second will air in late June.

Then on Thursday, July 4, Britons will vote between 7 a.m. and 10 p.m. local time, and as soon as polls close, votes will be counted. A winner is usually declared in the early hours of Friday morning.

Who is Keir Starmer?

Rishi Sunak’s rival for power is Labour leader Keir Starmer, who is heavily favored to become Britain’s new prime minister in July.

A former, well-respected human rights lawyer who then served as Britain’s most senior prosecutor, Starmer came into politics late in life. He became a Labour MP in 2015 and less than five years later was the party’s leader, following a stint as shadow Brexit Secretary during Britain’s protracted exit from the European Union.

Starmer inherited a party reeling from its worst electoral defeat in generations, but he prioritized an overhaul of its culture – staring down left-wing supporters of former leader Jeremy Corbyn, and apologizing publicly for a long-running antisemitism scandal that had tainted the group’s standing with the public.

He has attempted to lay claim to Britain’s political center ground, and is described by his supporters as a principled, serious leader with a focus on tackling the systemic issues facing Britain. But his opponents, on both the left of his own party and the right of the political spectrum, say he lacks charisma and ideas, and charge that he has failed to set out an ambitious and broad vision for the nation.

Who else is standing?

Only Sunak or Starmer have a realistic chance of becoming prime minister, but their plans could be disrupted by a number of smaller parties.

Nigel Farage, the populist right-wing figurehead who leads Reform UK, announced he would stand for election early in the campaign – he previously declined to do so, in order to help former President Donald Trump campaign in the US election this fall – and his entry has helped the group peel away Tory support.

Farage has criticized Sunak’s record on migration, and his group has pulled close to the Tories in many polls. Holding on to that level of support come election day could cause a once-in-a-lifetime decimation of the Tories at the ballot box.

Meanwhile, as Farage attacks Sunak from the right, the Liberal Democrats, a centrist, pro-European group, have chipped away at Conservative support in affluent, southern parts of England.

Given Labour’s standing in the polls, Starmer is more equipped to take the fight to other groups. North of the border, he will look to end the Scottish National Party (SNP)’s generation-long dominance at the ballot box, capitalizing on a rocky period in the party’s recent history that has seen them replace two leaders in just over a year.

But he will need to be mindful of the Green Party, which has challenged him from the left and has attracted some younger liberal votes as a result.

In recent local elections, there was evidence too that Labour’s stance on Israel’s war against Hamas in Gaza had harmed the party in majority-Muslim areas.

What issues will decide the election?

The answer to that question will go some way in deciding the night’s winner.

Labour has been dogged in trying to define the election as a referendum on 14 years of Conservative rule, seizing on public fatigue with a party that has produced five prime ministers in that span and overseen Brexit, a stuttering economy and a series of sleaze scandals.

In particular, Starmer has spoken plenty about the cost of living hitting British families, and the state of the country’s overstaffed and stretched National Health Service (NHS).

Sunak, by contrast, has tried to focus on migration – his pledge to “Stop the Boats” hasn’t yet worked, but his flagship Rwanda policy has at least become law. And he has attempted to convince voters that the economy has turned a corner, and can’t risk a change in governance.

When will we know the results?

Once polls open on Thursday, the media in Britain is barred from discussing anything that could affect voting.

But the second voting stops, an exit poll will drop that sets the course for the night. The poll, done by Ipsos for the BBC, ITV and Sky, projects the seat breakdown of the new parliament, and it’s historically been very accurate.

The real results are counted throughout the night; the shape of the evening is usually clear by about 3 a.m. local time (10 p.m. ET on Thursday), and the new prime minister – if there is one – is often in post by noon.

But things can take longer if the result is close, or if key seats go down to the wire.

Either way, the infamously sudden handover in power will take place by the weekend, leaving the new government a few weeks to work on key legislation before parliament breaks for the summer.

For more CNN news and newsletters create an account at CNN.com