Media playback is unsupported on your device Media caption The moment PM called for general election
UK Prime Minister Theresa May has announced plans to call a snap general election on 8 June.
She said Britain needed certainty, stability and strong leadership following the EU referendum.
Explaining the decision, Mrs May said: "The country is coming together but Westminster is not."
Opposition leader Jeremy Corbyn said his Labour Party wanted the election, calling it a chance to get a government that puts "the majority first".
There will be a vote in the House of Commons on Wednesday to approve the election plan - the prime minister needs two thirds of MPs to vote in favour to hold a vote before the next scheduled election date of 2020.
Explaining her change of heart on an early election, Mrs May said: "I have concluded the only way to guarantee certainty and security for years ahead is to hold this election."
She accused Britain's other political parties of "game playing", adding that this risks "our ability to make a success of Brexit and it will cause damaging uncertainty and instability to the country".
"So we need a general election and we need one now. 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.
Media playback is unsupported on your device Media caption Jeremy Corbyn: "I want to lead a government that will transform this country"
"I have only recently and reluctantly come to this conclusion. Since I became prime minister I've said there should be no election until 2020, but now I have concluded that the only way to guarantee certainty and security for the years ahead is to hold this election and seek your support for the decisions we must take."
In a statement outside Number 10, Mrs May said Labour had threatened to vote against the final Brexit agreement, the Liberal Democrats had stated they wanted to "grind the business of government to a standstill", the SNP have said they would vote against the legislation that formally repeals Britain's membership of the EU - and "unelected" members of the House of Lords had vowed "to fight us every step of the way".
"If we don't hold a general election now, their political game-playing will continue and the negotiations with the European Union will reach their most difficult stage in the run up to the next scheduled election," she said.
Analysis: By BBC Political Editor Laura Kuenssberg
For months Theresa May and her team have played down the prospect of an early poll. The reasons were simple. They didn't want to cause instability during Brexit negotiations. They didn't want to go through the technical process of getting round the Fixed Term Parliaments Act.
They didn't want the unpredictability of an election race. And many in the Conservative Party believed there is so little chance of the Labour Party getting its act together before 2020 that they could carry on until then and still expect a sizeable majority.
There was also, for Theresa May, the desire to show that she will be a prime minister who sticks to her word. But the relentless political logic proved too tempting to hold to all of that.
Read Laura's full blog
The PM challenged the opposition parties: "This is your moment to show you mean it - to show you're not opposing the government for the sake of it, to show that you do not treat politics as a game.
"Let us tomorrow vote for an election - let us put forward our plans for Brexit and our alternative programmes for government and then let the people decide.
"The decision facing the country will be all about leadership. It will be a choice between strong and stable leadership in the national interest, with me as your prime minister, or weak and unstable coalition government, led by Jeremy Corbyn, propped up by the Liberal Democrats - who want to reopen the divisions of the referendum - and Nicola Sturgeon and the SNP."
Mr Corbyn said he welcomed the prime minister's decision, saying it would "give the British people the chance to vote for a government that will put the interests of the majority first", saying that this would include dealing with "the crisis" in housing, education funding and the NHS and pushing for an "economy that works for all".
He told the BBC: "I'm starting straight away and I'm looking forward to it and we'll take our message to every single part of this country... We're campaigning to win this election - that's the only question now."
Asked if he will be the next prime minister, the Labour leader said: "If we win the election - yes - and I want to lead a government that will transform this country, give real hope to everybody and above all bring about a principle of justice for everybody and economic opportunities for everybody."
Scotland's First Minister Nicola Sturgeon said she would be fighting the election "to win".
"I think the prime minister has called this election for selfish, narrow, party political interests, but she has called it and therefore I relish the prospect of getting out to stand up for Scotland's interests and values, standing up for Scotland's voice being heard and standing against the ability of a right wing Conservative party to impose whatever policies it wants on Scotland."
Media playback is unsupported on your device Media caption Lib Dem leader Tim Farron says the 8 June election presents a fantastic opportunity
In his response to Mrs May's announcement, Lib Dem leader Tim Farron tweeted: "This is your chance to change the direction of your country. 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.
"Only the Liberal Democrats can prevent a Conservative majority."
MPs known to be standing down at the election:
Tom Blenkinsop - Labour
Jim Fitzpatrick - Labour
Oliver Letwin - Conservative
Pat Glass - Labour
Kenneth Clarke - Conservative
Simon Burns - Conservative
Ronnie Campbell - Labour
Mrs May spoke to the Queen on the phone on Easter Monday to let her know of the election plan, the prime minister's official spokesman said. She also got the full backing of the Cabinet before calling the election.
Former prime minister David Cameron called Theresa May's decision to hold a snap general election "brave and right". In a tweet, he added: "My very best wishes to all Conservative candidates."
CBI director general Carolyn Fairbairn urged all political parties to "commit to working to ensure businesses can continue to trade easily with our EU neighbours, while seeking new opportunities around the world".
Foto de archivo de Theresa May en el 2015.
En la salida del  la Primera Ministra del   anunció el martes su plan de solicitar una elección general para el 8 de junio. May acusó a los partidos de la oposición de amenazar la agenda del gobierno en cuanto al  y citó la necesidad de que el  esté unido durante las negociaciones sobre los detalles del Brexit, la salida del Reino Unido de la .

En virtud de la  los miembros del Parlamento deben aprobar la elección extraordinaria por dos tercios de los votos a favor. La votación tuvo lugar el miércoles en la Cámara de los Comunes, aprobándose la moción para celebrar una elección anticipada por 522 a 13 votos.

Si su  sigue las expectativas de los encuestadores, May —quien se convirtió en la Primera Ministra luego de la renuncia de  tras el resultado de la votación del Brexit— ampliaría su mayoría en la . El opositor  está detrás en las encuestas, con la mitad de partidarios comparado con los que cuenta el partido Conservador, según una encuesta divulgada recientemente por  en nombre de ''''.

La medida ha sido un cambio completo respecto de declaraciones anteriores, ya que la Primera Ministra dijo anteriormente que no tendría lugar una elección anticipada.

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