Freddy Matungulu of the Lamuka coalition, which had consistently staged protests against the long and iron-fisted rule of Tshisekedi's predecessor Joseph Kabila, confirmed on Friday that he had been offered the prestigious job.
"It pleased the head of state to designate me to assume the mandate of the DRC," said the former economist, who has also worked at the World Bank.
The Bank will have to formally approve his candidacy.
"I responded favourably to his call," Matungulu said, expressing his "gratitude" for this "act of friendliness."
The retired World Bank official said he was now "keeping a distance from my activism, including in Lamuka."
Social media was awash with speculation from ordinary Congolese whether this was a way of dismantling Lamuka.
The coalition views Tshisekedi as a puppet of Kabila. It now only has four of the original six co-leaders, all of whom are political heavyweights in the Democratic Republic of Congo.
Lamuka's remaining leaders now are Martin Fayulu who claims victory in the December election won by Tshisekedi; Moise Katumbi -- the powerful former governor of the mineral-rich Katanga region; Jean-Pierre Bemba, an ex vice-president and erstwhile warlord and former PM Adolphe Muzito.