Garang was over the weekend sworn in to the post of vice president as a new power-sharing constitution came into force in a bid to put a final seal on two decades of civil war between the Sudan People's Liberation Movement/Army (SPLM/A) and the Khartoum government.
"Change will happen, this change for sure will be positive," said Salah Barqueen, a senior official from the Eastern Front, which last month launched a major military offensive against the government in the Red Sea state.
Izzedine Baggi, a senior official from the Justice and Equality Movement (JEM), which together with the Sudan Liberation Movement, have been fighting the government in the the western region of Darfur for more than two years, opted for a "wait and see" stance.
"John Garang must take care of the Darfur problem. We don't have any problem with Dr Garang," Baggi said. " For now, it's wait and see, the coming days will tell us everything."
The Eastern Front, formed in February 2003, mainly comprise of rebels from Beja Congress and Free Lions and other small insurgent groups.
The Beja Congress first took up arms against Khartoum in 1994 and now controls the region north of the town of Kassala near the Eritrean border and since then the region has been a theatre of sporadic fighting.
Insurgents in both western and eastern regions of Sudan are fighting to end years of alleged marginalisation by successive Islamic governments in Khartoum.