The Umma-NUP coalition had collapsed by October 1965, owing to a disagreement over whether Mahgoub, as prime minister, or Azhari, as president, should conduct Sudan's foreign relations.

Mahgoub had continued in office for another eight months but resigns in July 1966 after a parliamentary vote of censure, which splits Umma.

A traditional wing led by Mahgoub, under the Imam Al Hadi, al Mahgoub's spiritual leadership, opposes the party's majority.

The latter group professes loyalty to the Imam's nephew, the younger Sadiq al Mahdi, who is the Umma's official leader and who rejects religious sectarianism.

Sadiq becomes prime minister with backing from his own Umma wing and from NUP allies.