SDLP deputy leader Nichola Mallon could be in trouble in North Belfast with her seat set to be picked up by Alliance's Nuala McAllister, several sources tell Belfast Live.
Such an outcome would be a significant loss for the SDLP and could signal further losses the party was not expecting across Northern Ireland.
It was previously thought Sinn Fein could be vulnerable to losing one of its two seats in the constituency.
Read more: Follow the results LIVE as they come in
However, the party is said to have balanced its vote well between its two candidates, Gerry Kelly and Carál Ní Chuilín, putting the party on course to retain both seats.
Ms Mallon has also been serving as Infrastructure Minister for the past two years and under Stormont rules, if a sitting Executive Minister fails to get re-elected, the legislation is clearly defined.
The vacated seat returns to the political party which nominated the Minister and that party then has seven days to nominate a replacement.
The DUP and Sinn Fein are vying for top spot at Stormont, which comes with the entitlement to nominate the next first minister.
A unionist party has always taken the most seats in the Assembly, and previously the Stormont Parliament, since the formation of the state in 1921.
While the office of the first and deputy first minister is an equal one with joint power, the allocation of the titles is regarded as symbolically important.
The Northern Ireland Protocol has cast a long shadow over the election campaign following the resignation of First Minister Paul Givan in February in an effort to force the UK Government to act over the post-Brexit trading arrangements.
This action left the Executive unable to fully function.
While ministers remained in post, they were restricted in the actions they could take.
The first of the 90 MLAs are expected to be returned by Friday afternoon but counting is set to continue into the early hours of Saturday.
Some 239 candidates are running across 18 constituencies.
Read more: Political party leaders cast ballots as race for Northern Ireland Assembly hots up
Read more: Review of Stormont parties' Assembly election broadcasts
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