General Election 2019: Decision day as key Northern Ireland constituencies hang in the balance
Northern Ireland's five main party leaders have made last-minute appeals for support as voters go to the polls in a Westminster election which could see several seats switch hands.
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A total of 1,343 polling stations open at 7am, and voters have until 10pm to cast their ballots. North Belfast and Foyle will be the most closely watched races. North Down, South Belfast, South Antrim and Fermanagh and South Tyrone are also highly competitive.
Counting will take place overnight, with the first result expected after 1am. However, some results may not be declared until after 4am.
Chief Electoral Officer Virginia McVea said: "The count will begin as soon as the first ballot boxes arrive at the count centres.
"We're expecting the first to arrive in Belfast around 10.30pm. The later boxes will come from the likes of Fermanagh, Newry and Armagh. We're hoping the first results will be declared in the early hours of Friday."
In her message to voters, DUP leader Arlene Foster said: "In 2017, people across Northern Ireland voted DUP in unprecedented numbers.
"They returned a strong DUP team to the House of Commons who were able to stand up for Northern Ireland and deliver £1.5bn for schools, roads and hospitals.
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"We have a 12-point plan for the future. While others talk about delivery, we have delivered and want to deliver more. If we are to get NI moving again and deliver our plan, we need every pro-Union voter to unite around the DUP and maximise the influence Northern Ireland can have in Westminster."
Sinn Fein vice president Michelle O'Neill said: "This election is the most important in a generation.
"A strong vote for Sinn Fein means your voice will continue to be heard loud and clear where it counts - in Brussels, Dublin, Downing Street and in Washington.
"We will be your voice in protecting the all-Ireland economy, protecting the Good Friday Agreement and preventing any hardening of the border. We will stand up to the Tories in London. We will stand up for equality, rights and for decent public services in Stormont."
SDLP leader Colum Eastwood said: "This is a once in a generation election. After three years of being misrepresented or unrepresented, people here have the power and the opportunity to send MPs to Westminster who will vote against Brexit and vote against Boris Johnson.
"They also have the opportunity to send a message to the DUP and Sinn Fein that it's time to get back to work to deliver pay parity for healthcare workers, to ensure our schools have the resources they need and to properly invest in jobs and infrastructure across the North.
"The polls are narrowing. We're now strongly in the territory of a hung parliament where every vote will count in the fight to stop Brexit. If you turn up for us, SDLP MPs will turn up for you."
UUP leader Steve Aiken said: "For too long, the DUP have been the sole voice of unionism in the House of Commons.
"Unionism can't afford any more complacency by elected representatives in Westminster. Unionism can't afford to make any more strategically damaging mistakes such as the DUP agreeing to a regulatory border in the Irish Sea.
"That's why I'm asking voters across Northern Ireland to vote for UUP candidates who will put the Union first."
Alliance leader Naomi Long said voters had the chance to send a message to the DUP and Sinn Fein.
"The DUP, in their partnership with the Tories, have backed a hard Brexit and in doing so risked plunging the economy into chaos and wrecking the Good Friday Agreement," she said.
"Sinn Fein, meanwhile, will not even turn up to vote against it. Brexit is not a green or orange issue and Alliance is not a green or orange party.
"That's why Alliance is best placed to unite people across the community again."
A total of 102 candidates are contesting 18 constituencies here, with 1,293,971 people eligible to vote.
Fewer people are using postal or proxy methods to vote, according to Electoral Office figures.
A total of 16,969 people have received a postal vote, down from 23,687 in the Westminster election two years ago. Fewer proxy votes have also been arranged, down from 11,707 in 2017 to 8,820 this year.