Mark Durkan is to deliver his first leader's speech to the SDLP conference after taking over from John Hume.
The Stormont Deputy First Minister has not been challenged for the post.
The party will also select a new deputy leader.
Voting closed last night at 6pm, with the ballots kept in a safety deposit box in the Slieve Donard Hotel where the annual conference is taking place.
The five candidates vying for the deputy leadership are: Stormont Employment and Learning Minister Sean Farren, Agriculture Minister Brid Rodgers, junior minister Denis Haughey, North Belfast Assembly member Alban Maginness and Down District councillor Margaret Ritchie.
The result is expected before lunchtime.
Mr Durkan, who is also Northern Ireland's Finance Minister, is assuming control of the SDLP just five days after he was elected along with Ulster Unionist leader David Trimble to head the North's power-sharing government.
The new SDLP chief is expected to mark out clear ideological territory between his party and Sinn Fein in his first leader's speech.