Mike Nesbitt last night at the Park Avenue Hotel in east Belfast after he announced his resignation as leader of the Ulster Unionist Party. Photo Colm Lenaghan/Pacemaker Press

As counting continued into the night in several constituencies, it became clear that every unionist leader had suffered in the face of a resurgent nationalist electorate.

Every major unionist party saw big losses, prompting Ulster Unionist leader Mike Nesbitt to dramatically announce his resignation at 8pm last night even before counting had finished.

By contrast, DUP leader Arlene Foster gave no indication that she is considering resignation, speaking about going into negotiations with Sinn Fein where there is “work to be done”.

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But in the next Assembly – if indeed those negotiations result in devolved government returning in the coming weeks – the DUP faces Sinn Fein breathing down its neck.

What was once a 10-seat gap between the parties is now only a single seat.

The party seat breakdown was as follows, with first preference votes in brackets:

DUP 28 (225,413)

Sinn Féin 27 (224,245)

SDLP 12 (95,958)

UUP 10 (103,314)

Alliance 8 (72,717)

Green Party 2 (18,527)

Others 3

Unionism came back with 40 seats (if Claire Sugden is counted as a unionist) – six short of a majority in the smaller 90-seat Assembly.

Nationalism was only a seat behind, with 39 seats.

Mr Nesbitt fell upon his sword even before there had been any groundswell for him to leave, knowing that his position was untenable, having presided over losses which could see the UUP down to 10 seats in an election where his party expected to gain on the 16 seats they had in the last Assembly.

In the presence of his wife Lynda, his son, UUP chairman Lord Empey and the party’s MEP, Jim Nicholson, he told journalists at the Park Avenue Hotel in east Belfast that after almost five years as UUP leader he would be resigning.

Mr Nesbitt said that “the buck stops here” in terms of his leadership.

The former broadcaster said that it would be the “height of hypocrisy” if he did not take “full responsibility” for his party’s performance, particularly because he has for weeks been calling on his DUP rival to take responsibility for the consequences of her actions in setting up the disastrous RHI scheme – which led to the election being called.

Mr Nesbitt said the electorate had rejected his hope for a post-sectarian vote.

“We will get there,” he said.

“Some day Northern Ireland will vote as a normal democracy. We will vote in a post-sectarian election but it’s now clear it will not happen during the duration of my political career.”

By contrast, a resurgent Sinn Fein saw its vote increase across the Province, holding its almost all its 28 seats despite the total number of Assembly seats being cut from 108 to 90.

Sinn Fein’s new Northern Ireland leader, Michelle O’Neill – who took over from the ill Martin McGuinness in January – was in confident form.

She said: “The vote has increased. I think that is because people knew that action needed to be taken, they have had their say, we now need to get down to the business of fixing what’s wrong and delivering for all citizens.”

Last night the DUP’s Edwin Poots said that “unionism needs to reflect where it’s going” and said that the election had left unionism weaker.

North Antrim DUP MP Ian Paisley told BBC Radio 5Live that while “Arlene Foster does need to reflect”, he believes that her position as leader of the DUP is secure.