Sadiq Al-Mahdi as president of the Unified National Front opposition party contributed to the downfall of the Aboud dictatorship in 1964. That same year he led a campaign to promote political activity, develop political Islam, and reform the party by expanding its base and promoting democracy behavior.

Despite his efforts towards a democratic government, there was another coup d´état in 1969 that led to a dictatorship referred to as the May Regime. After being arrested by the military government, he was exiled to Egypt, and detained in Sudanese prisons repeatedly until 1974.

While in exile, he formed the National Democratic Front (NDF), comprised of Umma, the Democratic Unionist Party, and the Muslim Brotherhood. Through his efforts, the NDF was able to make an accord of national reconciliation in 1977 with the May Regime that mandated democratic reform. The accord had little effect, and Al-Mahdi continued his democratization efforts despite his arrest in 1983.

He was released in December 1984, and led the opposition from within that drove the revolution of April 1985. As President of Umma he won the general elections for the Prime Minister of Sudan in 1986, a position he retained until the government was overthrown in 1989. After being detained, imprisoned and tortured, Al-Mahdi went into exile to lead the opposition in 1996, but returned to Sudan in 2000. In 2002 he was elected as the IMAM (religious leader) of ALANSAR. In 2003 he signed the Cairo Declaration for peace and democratic transformation. The Khartoum Regime initially welcomed but later refused to implement the Declaration.

Currently, Al-Mahdi continues his mobilization efforts to restore peace and democracy to Sudan, and to solve the dialectic between modern life and religious revival in the Muslim World.