Theresa May has announced she would like to hold a snap general election on Thursday June 8.
In an unexpected speech outside 10 Downing Street on Tuesday morning, the prime minister said she will tomorrow ask parliament to allow her to go to the country.
May said an election was needed to "secure the strong and stable leadership the country needs to see us through Brexit and beyond".
The prime minister added: "We need a general election and we need one now."
An election had not been due until 2020. And Downing Street has repeatedly denied any suggestion that May might attempt to call an early poll.
The latest polls suggest the Conservative Party will increase its majority over Jeremy Corbyn's Labour.
Justifying her change of mind, May said an election was the "only way to guarantee certainty and stability for the years ahead" as the Brexit process begins.
She said: "The country is coming together but Westminster is not. Labour have threatened to vote against the final agreement we reach. The Lib Dems have said they want to grind the business of government to a standstill. Unelected members of the House of Lords have vowed to fight us every step of the way."
To hold a general election, the government needs to win the support of two thirds of MPs.
"Tomorrow I will move a motion in the House of Commons calling for a general election to be held on the 8th of June," May said.
Jeremy Corbyn: 'I want to lead a government'
Corbyn said Labour will vote in favour of the motion and allow an election to go ahead.
"I welcome the Prime Minister's decision to give the British people the chance to vote for a government that will put the interests of the majority first," he said.
"Labour will be offering the country an effective alternative to a government that has failed to rebuild the economy, delivered falling living standards and damaging cuts to our schools and NHS.
"In the last couple of weeks, Labour has set out policies that offer a clear and credible choice for the country. We look forward to showing how Labour will stand up for the people of Britain."
Polls point to Tory victory
A YouGov survey for The Times on Monday gave the Conservatives a huge 21 point lead over Labour.
The survey showed May on 44% with Jeremy Corbyn's Labour trailing with just 23%. It is Labour's worst position according to YouGov since 2009.
Lib Dem leader Tim Farron said an election was a "chance to change the direction of our 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," he said. "Only the Liberal Democrats can prevent a Conservative majority."
Scottish First Minister Nicola Sturgeon said the Tories "see a chance to move the UK to the right, force through a hard Brexit and impose deeper cuts" The SNP leader said added: "Let's stand up for Scotland".
Ukip leader Paul Nuttall said he would take his party's "positive message to the country" but said May had made a "cynical decision" based on the "weakness of Corbyn's Labour Party rather than the good of the country".
"There is also the prospect of a slew of Tory held by-elections caused by the seeming systematic breach of electoral law at the last election, predominantly in places where UKIP were pressing the Conservatives hard," he said.
"We are in the midst of Brexit negotiations so this election will provide a perfect opportunity for the 52% to vote for UKIP the only party wholeheartedly committed to a clean quick and efficient Brexit."