SDLP leader Mark Durkan has said he intends to stand aside as party leader after the next Westminster general election, which is expected around May next year.
Mr Durkan said he will defend his seat in the Foyle constituency but does not believe he should continue to hold a dual mandate, by also holding a seat in the Six-County Stormont Assembly.
He made the comments on BBC radio.
Mr Durkan said he already indicated he did not want to continue as SDLP leader after his 50th birthday.
The 49-year-old replaced John Hume as leader of the SDLP in 2001 and four years later, as Derry’s elected representative at the London parliament.
He said: “My position is that if I am elected again to Westminster as MP for Foyle I will be stepping down from the Assembly.
“I’ve said that openly on the record because I don’t believe that that you can sustain dual mandates any longer.”
Mr Durkan added that he believed the Six Counties would be significantly impacted by cuts in public expenditure after the next election, and this had influenced his decision.
“If there is a Tory government elected, the implications in terms of the welfare system and other matters are such that I think there is more work to done at Westminster now.
“I think in that instance I need to be a full time MP for Foyle.”
He also said that he did not believe that the SDLP, as a nationalist party, could “long be led from Westminster” but said he would continue to play a strong leadership role in the party.