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British Prime Minister Theresa May stunned her nation on Tuesday with a call for a snap election on June 8. May's bid requires approval by two-thirds of Parliament — a vote that is likely a formality. If it goes ahead, it will mark Britain's third general election in two years, following parliamentary elections in 2015 and Britain's Brexit referendum last June.

Why is there yet another election now?

In remarks delivered outside 10 Downing Street, May said her government needed a new mandate as Britain enters tense negotiations with the European Union over the terms of departure from the bloc. May only became prime minister after her predecessor, David Cameron, resigned last year in the wake of the Brexit referendum, and she may desire direct validation from voters.

“I have concluded the only way to guarantee certainty and stability for the years ahead is to hold this election and seek your support for the decisions I have to make,” said May.

Why did May change her mind?

As my colleague Adam Taylor observed, the move contradicts repeated statements from May that elections would only be held when Parliament's term expires in 2020. But May, it seems, could be sensing political opportunity. Her Conservatives command a slender majority of 17 seats in Parliament, but opinion polls show May's popularity rising and the Conservatives in a strong position to extend that margin — particularly at the expense of a Labour Party in disarray. It also helps to stage the vote before a divided British public further reckons with the price of leaving Europe.

“We need a general election, and we need one now,” said May, “because we have at this moment a one-off chance to get this done while the European Union agrees its negotiating position and before the detailed talks begin.”

What does it mean for Brexit?

If May and the Conservatives win big — as many expect — then the election would strengthen her hand as she knuckles down for talks with Brussels and seeks what's been dubbed a “hard Brexit” — abandoning access to the European single market and many other E.U. privileges. If opposition parties do well, it may temper those negotiations and force May into concessions. But what is unlikely to happen in any scenario is a reversal of Brexit.

“May has seized on this moment to reset her clock as Brexit negotiations get underway, but the dynamics just aren’t there to redo last year’s referendum,” explained my colleague Michael Birnbaum. “There’s no single leader who could rally anti-Brexit voices in a credible threat to May. How bad is it? Labour leader Jeremy Corbyn’s reaction to the snap elections avoided any mention of Brexit, Britain’s central political issue this generation, in a sign of his fears that trying to reverse the 2016 decision could alienate a big part of his base.”

What's wrong with Labour?

The leading opposition party is a mess and could be on track for its worst electoral showing since 1918. In each of the previous national elections, it saw some of its working-class base drift away toward pro-Brexit, anti-immigrant platforms. A by-election in February for a constituency in northern England seemed a grim bellwether: The seat, which had been in Labour hands since 1935, was won by a Conservative candidate.

Part of the problem rests in the profile of the current party leader, Jeremy Corbyn, a staunch leftist who spent months locked in internecine conflict with Labour's more moderate wing. “A recent poll showed that, in a head-to-head matchup between May and Corbyn, not even a majority of Labour voters would want Corbyn as their prime minister,” reported my colleague Karla Adam.

Corbyn has been lukewarm in his opposition to Brexit. On Tuesday, he supported May's decision for fresh elections, but he now faces another backlash within his party, as some Labour members of Parliament urged him to reconsider acquiescing to the prime minister's cynical political calculation.

Can any other party challenge May?

Not really. The far-right United Kingdom Independence Party, which once led the calls for Brexit, has seen much of its raison d'etre co-opted by the Conservatives. The Liberal Democrats, decimated in the 2015 election, are hoping to reassert themselves.

“If you want to avoid a disastrous ‘hard Brexit.' If you want to keep Britain in the single market. If you want a Britain that is open, tolerant and united, this is your chance,” said Lib Dem party leader Tim Farron. But even if they do gain ground, it'll likely be as much to the detriment of Labour as the Conservatives.

And what about Scotland?

Nicola Sturgeon, the leader of Scottish National Party, said May's decision to call for an election was a “huge political miscalculation.” But her party is expected to retain its dominance over Scotland's seats in Westminster and may be even more emboldened to push for a renewed independence bid.

May turned down a request by Sturgeon last month for a second independence referendum in Scotland “on the basis that it would be irresponsible to hold such a vote when the terms of Brexit were not yet clear,” the Economist observed. “It is hard to see why the same cannot be said of holding a general election now in Britain.”

Meanwhile, a new general election may further deepen an ongoing political crisis in Northern Ireland.

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