Opposition presidential candidate Martin Fayulu has warned election officials in the Democratic Republic of Congo not to "disguise the truth" as tensions mount over the delayed result.
His preferred successor, former interior minister Emmanuel Shadary, is facing strong opposition from Mr Fayulu, an ex-oil tycoon, and Felix Tshisekedi, son of a veteran opposition leader.
The choice fuelled accusations that Kabila - concerned about possible retribution - would use Shadary to protect his interests after the vote.
In November 2018, following three days of talks in Geneva to bridge rifts in the opposition, seven opposition leaders picked Fayulu as their joint candidate for the elections to replace Kabila.
A CENI source and a diplomat said they expected results to be announced later on Wednesday. Fayulu received more than 6 million votes, or 34 percent.
The party behind the other top opposition candidate, Tshisekedi, said it suspects the electoral commission to be working in concert with Congo's ruling party under "purely political motivations".
The announcement came as riot police were deployed in the capital, Kinshasa, amid fears of a disputed result in the December 30 vote marked by accusations of vote fraud.
Kabila has ruled since 2001 in the troubled nation rich in the minerals key to smartphones around the world and has amassed vast wealth.
If Tshisekedi's stunning victory is confirmed by the constitutional court, he will become the first Congolese leader to take power at the ballot box since Prime Minister Patrice Lumumba, who was toppled and killed in a coup shortly after independence in 1960. The electoral commission said this was due to an Ebola outbreak and violence there, but it means about a million people have been disenfranchised because the new president is due to be sworn in this month.
And this is not the first sign of discontent between Fayula and Tshisekedi, which began even before the presidential elections.
"The influential Catholic Bishop's Conference, which fielded 40,000 observers, says the outcome of the much-anticipated vote is at odds with its tally".
Congo's government cut internet service the day after the vote to prevent speculation on social media.
He is known as the "people's soldier" for leading protests against President Kabila.
How will Congolese citizens react?. Some said they would be happy as long as Fayulu or Tshisekedi won, while recalling the violence that followed past disputed elections.
"The CENI plans to devote 24 to 48 hours to this task, after which time the CENI will schedule the announcement of the provisional results", he said. He was less visible in campaigning than Fayulu and did not make himself available to reporters after the vote.