Sinn Fein is braced for a historic victory as the first votes are counted in the election of the Northern Ireland Assembly.
Voters are choosing a new 90-seat Assembly, with polls suggesting the Irish nationalist party, and former political wing of the IRA, could win the largest number of seats - and the post of first minister.
It would be the first time an Irish nationalist party has emerged as the largest at Stormont.
As of 8.20pm, just 28 seats have been announced - with Sinn Fein having won 16, the Democratic Unionist Party four, the Ulster Unionist Party three, the Social Democratic and Labour Party one and the Alliance Party three.
But the final results are not expected until late this evening, or even early on Saturday morning.
The Northern Ireland Assembly is reliant on power-sharing, which means Sinn Fein will need the support of the unionists in order to govern.
Mary Lou McDonald, the Sinn Fein president who is leader of the opposition in the Republic of Ireland, told Sky News that preparation for a referendum on a united Ireland "needs to happen now".
"We want this to happen in a way that is orderly, that is planned, that is democratic and that is peaceful."
She said Sinn Fein's Michell O'Neill would, if she became first minister, lead "in a way that is thoughtful and inclusive and progressive" and called on the DUP to "reflect very carefully on their next move".
"There is no alternative other than to work together," she said.
DUP loses support over Brexit
Sir Jeffrey Donaldson, leader of the DUP, when asked if he would support a Sinn Fein first minister said first there must be progress on the Northern Ireland Protocol.
The DUP has lost support among unionists over its response to Brexit and trading arrangements concerning Northern Ireland.
This has caused a split of votes between the unionist parties, the DUP, the UUP, and the TUV (Traditional Unionist Voice).
Earlier, speaking to Sky News ahead of his imminent election to the Assembly, Sir Jeffrey, said: "I am afraid the message here is that a divided unionism is not a unionism that is going to win elections, therefore I think we need to tackle the divisions within unionism, we can't go on like this.
"I hope by the next election that we will see a more united unionism."
He added: "We are separated from Great Britain by a customs border and that makes us second-class citizens in our own country. That is not consistent with the Good Friday Belfast agreement."
However, Sir Jeffrey currently sits in Westminster as an MP and will need to decide in the next seven days which seat he wishes to resign - and could end up resigning from the one he just won.
The party could boycott the power-sharing government rather than see a nationalist first minister.
DUP MP Ian Paisley said there would be no devolved government in Northern Ireland while issues around the Northern Ireland Protocol remain unresolved.
Speaking at an election count centre in Jordanstown, Mr Paisley said: "I think the elephant in the room is the protocol.
"Until we get this matter fixed we can have whatever election we want but there is not going to be a government until we get that protocol issue resolved.
"Hopefully today will be a focus for the government that they have to now resolve this, not just for unionists but for everyone. The protocol hurts us all."
Referendum on Irish unity
Unionist parties have won every Stormont election for 100 years - ever since Ireland was partitioned in 1921 - and a nationalist victory would raise constitutional questions.
Such a result could see proponents of a referendum on Irish unity make the case for a vote with renewed vigour.
Speaking to reporters shortly before her election was announced, Sinn Fein vice-president Michelle O'Neill said she was feeling "very positive".
Asked about the possibility of her taking the first minister role, she said: "It is very early to say, let's get all the votes counted."
She said that Sinn Fein wanted to "work in partnership with others".
"That is the only way we will achieve much, much, more for people here, whether in terms of the cost-of-living crisis or trying to fix our health service".
Alliance surge cost UUP and SDLP seats
Meanwhile Alliance leader Naomi Long dedicated her re-election to her father-in-law who recently died. Her party is on track to win seats that it has not before - at a cost to the UUP and nationalist SDLP.
"It's been quite an emotional election campaign for me," she said.
"I lost my father-in-law in the last few weeks, and we buried him yesterday. I just want to dedicate this win to him because without family I could not do what I do, and without their support, I would not be where I am.
"I am just absolutely thrilled that I've polled so well and I really look forward to later on today and seeing all my colleagues bringing it home."