Published Saturday, 05 November 2011
The South Belfast MP thanked all those who voted for him.
"This is the proudest moment of my political life," Dr McDonnell told party delegates at the Ramada Hotel on Saturday.
He saw off the challenge of three party colleagues for the leadership - Patsy McGlone, Alex Attwood and close runner-up Conall McDevitt.
Only 36 votes separated Mr McDonnell and Mr McDevitt in the final count.
Much talk in SDLP about Conall McDevitt's good performance. A leader in waiting, some are saying.
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Dr McDonnell thanked his challengers and pledged to lead the party to a political revival - he is the second leader to be elected in less than two years, and had finished runner-up in 2009.
He had a stark message to the DUP and Sinn Féin in Saturday's victory speech.
"We helped arrive at an agreed Ireland in 1998," he said - referring to the signing of the Good Friday Agreement.
"The two parties that are now in power have turned that agreed Ireland and tremendous opportunity into a grubby little deal - they are like Afghan warlords dividing up the spoils."
He said he would restore the party to its position of relevance.
"For me the task is set," he told fellow party members.
"You've chosen me to lead the recovery and the renaissance of this party.
"I will do it. I want you to enjoy yourselves for the rest of the evening because tomorrow the work will have to start."
Ms Ritchie announced her plan to step down in September, in the wake of poor general and assembly election results.
First Minister Peter Robinson took to Twitter to congratulate the new SDLP leader.
"Well done Alasdair. Look forward to working with you," the DUP leader wrote on Saturday evening.
Sinn Féin president Gerry Adams said: "I wish Alasdair McDonnell well. I hope the new leader will display a positive, constructive and forward looking attitude."
Upper Bann MLA Dolores Kelly was elected the new SDLP deputy leader.
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