Video report by Political Editor Robert Peston
Prime Minister Theresa May has confirmed she wants to hold a snap General Election on June 8 after having a change of heart on going to the polls.
Mrs May said she had "only recently and reluctantly" come to the decision as she argued Westminster was too divided going into Brexit negotiations.
"The country is coming together but Westminster is not," she said, adding "division in Westminster will risk our ability to make a success of Brexit".
The announcement comes less than a month after Downing Street said an early election was "not going to happen".
Explaining her change of heart, Mrs May said: "I have concluded the only way to guarantee certainty and security for years ahead is to hold this election."
The prime minister said "political game-playing" would continue without a snap election and at a point when Britain's negotiations with the EU will reach their "most difficult stage".
"So we need a general election and we need one now," she said. "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."
Opposition party leaders have so far "welcomed" the PM's calls for an early election but also noted that it could be a "cynical" move.
Labour leader Jeremy Corbyn said the suggestion of a snap election could give the British people "the chance to vote for a government that will put the interests of the majority first."
Liberal Democrat leader Tim Farron said a potential election would be a a "great opportunity" and could mark a chance for the UK to alter which path it takes during Brexit negotiations.
Ukip leader Paul Nuttall said it was a chance for his party to share their message but deeclared it "a cynical decision driven more by the weakness of Corbyn's Labour Party rather than the good of the country."
Mrs May can formally call an early election if two-thirds of MPs in the House of Commons (391) vote for it.
Labour leader Jeremy Corbyn has previously indicated his party would support such a move.
The Conservative share of the latest voting intention figures (YouGov/Times)
The Labour share of the latest voting intention figures (YouGov/Times)
If approved it will be Mrs May's first test at the national ballot box after she succeeded David Cameron at Number 10 in July 2016.
Mr Cameron's resignation in the wake of the EU referendum result came 14 months after he led the Conservatives to outright election victory following five years of coalition government with the Lib Dems.
Downing Street last month ruled out a snap election amid mounting speculation the PM was considering an early vote rather than see out the full parliament before a national poll in 2020.
Conservative backbenchers have pressed Mrs May to take advantage of the sizeable current poll lead over Mr Corbyn's Labour in an attempt to build a greater Commons majority.
The most recent YouGov/Times poll on voting intention forecast a 21-point lead for the Conservatives over the leading opposition.
The Conservatives currently have a working government majority of 17 seats.
Downing Street had rebuffed the rumours at the time, saying: "There is no change in our position on an early general election, that there isn't going to be one... It is not going to happen."
A commanding election victory could give Mrs May a mandate both for her leadership and her negotiating position on Brexit before talks with the European Union start in earnest.