Railway workers and other protesters traveled by train from Atbara, the northern transport hub where the uprising began in December, to the capital, Khartoum, where they were welcomed by cheering crowds. They joined thousands of people gathered outside the military headquarters, where the protesters have held a sit-in since April 6.
"We came for the revolution. We are workers in the railway. The government let us down. So we want to send a message," said protester Abdel-Moneim Ibrahim who travelled from Atbara. Thousands of people poured into the streets to join marches and sit-ins in Khartoum's twin city of Omdurman and in the provinces of Kassala and South Kordofan.
In the eastern city of al-Qadarif, protesters held photos of people who have been killed in the uprising. Organizers of the protests say around 100 people have been killed by security forces since December.
Al-Bashir, who ruled Sudan for 30 years, was forced from office on April 11 after four months of protests led by the Sudanese Professionals Association, a group of private unions that is demanding a full and immediate transfer of power to a civilian council.
The SPA said security forces attempted to break up their gathering outside the military complex and that protesters saw bulldozers moving toward the sit-in. They called for fortifying the barricades around the sit-in.
The SPA suspended talks with the military over the weekend after the military council said it was consulting all of Sudan's political forces on a path forward. The protesters accuse the council of failing to make a clean break with al-Bashir's regime and of trying to marginalize the SPA by depicting it as one of many political factions.
The SPA says the head of the military council's political committee and its chief negotiator, Lt. Gen. Omar Zain al-Abdin, was the head of al-Bashir's party within the military and "is trying to bring back the deposed regime."
The protesters also say the military council has yet to recognize the Forces of the Declaration of Freedom and Change — a coalition led by the SPA and including other groups — as their representative. The protesters fear Islamists and other factions close to al-Bashir, who is now jailed in Khartoum, will be granted a role in the transition.
The military council has said it is in talks with all political parties to name a prime minister and civilian government to run the country for two years. The SPA has instead called for the formation of a legislative council — in which at least 40 percent of the membership would be women — to draft laws and oversee a Cabinet of technocrats until a new constitution is written. The SPA plans to announce its own civilian transitional council during mass rallies on Thursday.
In Cairo, meanwhile, President Abdel-Fattah el-Sissi hosted a meeting with Moussa Faki, the chairman of the African Union commission, and several other African leaders to discuss the situation in Sudan.
Bassam Radi, the spokesman for Egypt's presidency, said the leaders agreed to give Sudan's military three months to hand over power to a "civilian-led political authority" or face suspension from AU activities. The AU had initially given the military 15 days to transfer power to civilians.
Sudan's protesters have explicitly rejected what they call the "Egypt scenario," referring to that country's 2011 uprising and its aftermath. Egyptian protesters succeeded in forcing long-ruling President Hosni Mubarak from power, but the military then presided over a chaotic transition leading to the election of an Islamist president, Mohammed Morsi. El-Sissi led the military overthrow of Morsi amid mass protests against his rule in 2013, and has since rolled back freedoms gained in 2011.
Constitutional amendments expected to be approved in a referendum this week would allow el-Sissi to remain in power until 2030.
Magdy reported from Cairo.