Yunus Qanuni is seen by many as the main challenger to President Hamid Karzai in the October elections.
A former education minister in Mr Karzai's interim administration, he is an ethnic Tajik who has the backing of the powerful Defence Minister, Mohammed Fahim.
Mr Qanuni is a veteran of Afghan power struggles
Together with General Fahim and Foreign Minister Abdullah Abdullah, Mr Qanuni is the political and military heir of Ahmad Shah Masood, the Tajik commander assassinated by suicide bombers in September 2001.
Mr Qanuni was born in 1957 in the Panjshir Valley north of Kabul, but went to the capital to study.
He soon became involved in politics,
opposing the rule of President Daoud, who had overthrown King Zahir Shah in 1973.
Fighting the Soviets
Following the Soviet invasion in 1979, he returned to the Panjshir Valley and joined up with Ahmad Masood's forces.
He is said to have travelled to Pakistan to buy arms and secure funds for Mr Masood, known as the "Lion of the Panjshir".
In 1993, when the mujahideen took power in Kabul, he became joint defence minister in the government led by president Burhanuddin Rabbani.
The conflict between Afghan's warring factions was brought home to him when his car was blown up near Kabul in 1993, and he was seriously wounded.
Mr Qanuni impressed diplomats at the Bonn conference
After the fall of Kabul to the Taleban three years later, Mr Qanuni helped found the Supreme Council for the Defence of the Motherland, and later the United Islamic and National Front for the Salvation of Afghanistan.
Search for unity
He headed several Afghan delegations for talks with exiled leaders in Europe, including former king Zahir Shah, in an attempt to unite anti-Taleban factions.
Following Masood's assassination in September 2001, Mr Qanooni became the political head of the Northern Alliance's main Jamiat-e-Islami party.
He was named interior minister of the Northern Alliance when they re-entered Kabul on 13 November after the Taleban fled US-led forces, and headed their delegation to the Bonn talks.
At Bonn, diplomats were said to be impressed with his forceful speaking and negotiating skills.
But in a major setback to his political career, he was shifted from the interior ministry to education as part of a move by Mr Karzai to promote more ethnic Pashtuns to positions of power.
An upset Mr Qanuni threatened to resign but was persuaded to stay on.
Despite his powerful backers, he will find it hard to broaden his political appeal among groups beyond his Tajik community.
He has chosen as his running mates a Pashtunm, Taj Mohammed Wardak, and Sayid Husain Aalimi Balkhi, from the Shia minority Hazara community.