Stormont finance minister Mr Mark Durkan today announced his intention to stand for leadership of the SDLP.
The 41-year-old Foyle Assemblyman, who is now firm favourite to replace John Hume, said he was ready for the challenge.
Mr Durkan said that this week's announcement by Mr Hume and Mr Mallon presented a new and significant challenge to everyone in the party.
"I know that the party is yet again up to that challenge. This party will prove it has the values, the vision and the vibrancy to carry forward the achievements of the Agreement and the ambition for new and better political ways."
Despite being eclipsed by Sinn Féin as the largest nationalist party in the British General Election, Mr Durkan said the SDLP had not run out of energy.
"I am not John Hume. I make no apology for the fact I am not John Hume. The SDLP is going to have to move forward, not just in the party but as a wider society.
"We can carry forward the ideals and the inspiration that John Hume and Seamus Mallon have worked so hard for."
"I'm seeking the support of elected colleagues and fellow members of my party and offer to lead them through a period of development and change," he said.
Mr Durkan could go unchallenged for the leadership at the party's annual conference in November.
“People aren't ruling out the possibility of the challenge but he is regarded as the runaway favourite,” a source said.
His nomination follows the decision yesterday of Acting Deputy First Minister Seamus Mallon not to stand for the post and to step down as Deputy Leader. Sources close to Agriculture Minister Ms Brid Rodgers today appeared to rule out her mounting a challenge to Mr Durkan. However, they would not rule out that she would run for the post of deputy leader. "Brid has no plan to run for leader but she is considering what role she might play in the future," a source close to her said. "We just have to see what develops." The race to replace Mr Mallon as SDLP deputy leader will also include former Belfast Lord Mayor Mr Alban Maginness who declared his candidacy last night.
Employment Minister Mr Sean Farren, South Down MP Mr Eddie McGrady and Assembly members Mr Joe Byrne, Ms Patricia Lewsley and Mr Eamon O'Neill are also being tipped as possible candidates.
Mr McGrady was also not being ruled out running against Mr Durkan.
Party sources said SDLP chairman Mr Alex Attwood has so far ruled himself out of the contests.
PA