The SDLP is set to hold a leadership contest for the first time in its history after a second candidate threw his hat in the ring today. South Belfast MP Alasdair McDonnell has announced his intention to seek the leadership when Mark Durkan steps down next February. South Down MLA Margaret Ritchie is the only other party member to declare her candidacy so far. The winner of the contest will be SDLP's fourth leader after Gerry Fitt, John Hume and Mr Durkan.