The Sudanese Federal Umma Party announced today that it is withdrawing from government and pulling its representatives from executive and legislative positions.
The move comes amid nationwide protests against President Omar al-Bashir, who seized power in a 1989 military coup.
Party leader Ahmed Babiker Nahar called on President Bashir to step aside and form a transitional government.
Babiker told reporters at a press conference in Khartoum on Sunday that they decided to withdraw after the government disregarded their calls to refrain from using lethal force against peaceful protesters.
The party leader, who was once allied with President Bashir, said his party will work together with other political parties to achieve a national programme agreed upon by the people of Sudan.
Earlier this month, 22 opposition political parties and groups, including the Reform Now Party led by Ghazi Salah-Eddin and the National Umma Party faction led by Mubarak al-Fadil al-Mahdi demanded that Bashir transfer power to a transitional government that would set a suitable date for presidential elections.
The groupings, calling themselves the National Front for Change, said the current government failed to overcome the economic crisis.
Sudan has been rocked by anti-government protests that erupted on 19 December after a government decision to raise prices of bread and have since morphed into nationwide demonstrations calling for Bashir's ousting.
The government says at least 29 people have been killed during the protests but rights groups say the death toll is twice as high.