McDonnell may also take on Ritchie
SDLP leader Margaret Ritchie could face a second challenger after South Belfast MP Alasdair McDonnell said he is being urged to step forward.
This comes after the deputy leader Patsy McGlone confirmed speculation that he will stand against Ms Ritchie at the party's November annual conference.
Mr McDonnell, who was beaten to the top job in 2010, said he is being encouraged to put his name forward again, but he has yet to decide.
Ms Ritchie has been under growing pressure since the SDLP lost two seats in May's Assembly election, which followed growing internal criticism of her leadership and her media performances.
Mid Ulster MLA Patsy McGlone said: "There comes a time when change is needed for the greater good. It is one of those times."
Having taken soundings within party ranks, he said he had decided to "step up to the mark".
Mr McGlone has formed a campaign team and will soon hold an official launch for his bid to gather the internal support needed to seize the SDLP's lead role.
He called for a change in the style of leadership, in delivering a clear party message and in building an effective grassroots organisation, all of which he said he had achieved in his own electoral area.
"I do what it says on the tin. I have done it in my own constituency. So I don't just say what I am going to do. I do it. There is a hunger for change. People know that. Really what I am saying is give me an opportunity."
But after he announced his plans, Mr McDonnell confirmed he was coming under pressure to launch a leadership bid of his own. "Should the leadership of the SDLP open up, there is a large body of opinion urging me to go forward," said Mr McDonnell. "I am still talking to people and I'm listening to people."