Protest organisers have called for a march on the presidential palace in the capital Khartoum on Thursday, along with simultaneous demonstrations in several other cities.
Authorities say at least 24 people have died since the protests first broke out on December 19 after a government decision to triple the price of bread.
Rights group Human Rights Watch has put the death toll at 40, including children and medical staff.
The protests have escalated into nationwide anti-government demonstrations that experts say pose the biggest challenge to Bashir since he took power in an Islamist-backed coup in 1989.
“I have been demonstrating and will continue to demonstrate until this regime is overthrown,” vowed Adel Ibrahim, 28, who has participated in demonstrations in Khartoum.
“We are protesting to save our future and the future of our homeland.”
Protests initially broke out in the eastern town of Atbara, which has a history of anti-government sentiment, and within days spread to other provinces and then to Khartoum.
Cities like Port Sudan, Gadaref, Kassala and agricultural regions that previously backed Bashir saw protests calling for him to step down, while the western region of Darfur too witnessed rallies against the 75-year-old veteran leader.
Using social media networks to mobilise crowds, most protesters have marched chanting “Peace, freedom, justice”, while some have even adopted the 2011 Arab Spring slogan — “the people want the fall of the regime”.
Crowds of demonstrators, whistling and clapping, have braved volleys of tear gas whenever they have taken to the streets, witnesses said.
“There’s a momentum now and people are coming out daily,” said prominent Sudanese columnist Faisal Mohamed Salih.
“Even the authorities are astonished.”
– ‘We have to fight’ –
Although the unrest was triggered by the cut in a vital bread subsidy, Sudan has faced a mounting economic crisis in the past year, including an acute shortage of foreign currency.
Repeated shortages of food and fuel have been reported across cities, including in Khartoum, while the cost of food and medicine has more than doubled.
Officials have blamed Washington for Sudan’s economic woes.
The US imposed a trade embargo on Khartoum in 1997 that was lifted only in October 2017. It restricted Sudan from conducting international business and financial transactions.
But critics of Bashir say his government’s mismanagement of key sectors and its huge spending on fighting ethnic minority rebellions in Darfur and in areas near the South Sudan border has been stoking economic trouble for years.
“If this regime continues like this, we will soon lose our country, which is why we have to fight,” said Ibrahim, who has been looking for a job for years.
An umbrella group of unions of doctors, teachers and engineers calling itself the Sudanese Professionals’ Association has spearheaded the campaign, calling this week the “Week of Uprising”.
“Protesters don’t even know the organisers by names, but they still trust them,” said Salih.
– ‘Protests not popular’ –
Sudanese authorities led by the feared National Intelligence and Security Service (NISS) have cracked down on protesters, drawing international criticism.
More than 1,000 people, including protesters, activists, opposition leaders and journalists have been arrested so far, rights groups say.
Bashir has remained steadfast in rejecting calls for him to resign.
“Demonstrations will not change the government,” he told a rally in Darfur on Monday as supporters chanted “Stay, stay”.
“There’s only one road to power and that is through the ballot box. The Sudanese people will decide in 2020 who will govern them,” said Bashir, who is planning to run for the presidency for the third time in elections to be held next year.
Two uprisings in Sudan in 1964 and 1985 saw regimes change within days, but experts say this time protesters have a long road ahead.
“At the moment, Bashir appears to have the majority of the security services on his side,” said Willow Berridge, a lecturer at Britain’s Newcastle University.
Bashir’s ruling National Congress Party has dismissed the demonstrations.
“There are some gatherings, but they are isolated and not big,” party spokesman Ibrahim al-Siddiq told AFP.
The International Crisis Group think-tank said Bashir might well weather the unrest.
“But if he does, it will almost certainly be at the cost of further economic decline, greater popular anger, more protests and even tougher crackdowns,” it said in a report.
Salih said protesters appeared to be determined.
“But the one who tires first will lose,” he said.