Representatives for Sudan Call, a coalition of political and armed opposition forces, urged its members to boycott the country's upcoming presidential and legislative elections in an effort to discredit Sudan’s ruling National Congress Party (NCP). Sadiq al-Mahdi, leader of the opposition National Umma Party (NUP), accused the NCP of trying to fix the April 13 elections, the Sudan Tribune reported.

“Thus the Sudan Call forces appeal on the masses of our people to escalate the resistance against the fake elections and overlook its results and to continue the resistance campaigns until the overthrow of the regime,” Mahdi said Sunday, describing the regime of Sudanese President Omar al-Bashir as “volatile.”

The Sudan Call agreement is aimed at uniting the mainstream opposition against Bashir’s regime, according to the Sudan Tribune. The Sudan People’s Liberation Army-North (SPLA-N) opposition signed the declaration in December, along with other political parties, civil society organizations and armed groups. Although the Sudan Call’s armed wing is boycotting the elections, the coalition has denied the SPLA-N’s campaign to disrupt voting.

SPLA-N spokesman Arnu Lodi told Agence France-Presse forces of their political wing “ambushed and captured a vehicle loaded fully with ballot boxes” Saturday in South Kordofan, one of Sudan’s conflict-hit regions.

Sudanese Defense Minister Abdel Rahim Mohammed Hussein said Friday the army “will not allow the rebels to impede the elections,” according to AFP. Violence from insurgencies in Blue Nile, South Kordofan and the western region of Darfur has recently escalated ahead of the nationwide polls. The fighting has displaced at least 20,000 people since the beginning of March alone.

Bashir -- who took power during a 1989 coup and has been charged by the International Criminal Court for alleged war crimes -- has vowed to bring peace to the North African Arab republic, either by force or through diplomacy. Sudan Call representatives were scheduled to meet with members of NCP in Addis Ababa, Ethiopia, at the end of March, but the ruling party did not attend and said the dialogue would take place after the elections, AFP reported.