The national assembly majority sharply reduces the chances of dramatic reforms under the declared presidential election winner, opposition leader Felix Tshisekedi. The election runner-up, Martin Fayulu, has accused Tshisekedi of a backroom deal with Kabila to win power in the mineral-rich nation as the ruling party candidate did poorly.
Congolese face the extraordinary situation of a presidential vote allegedly rigged in favor of the opposition. "This is more than an electoral farce; it's a tragedy," the LUCHA activist group tweeted Saturday, noting the ruling party majority in both national assembly and provincial elections.
Fayulu, a businessman who has been vocal about cleaning up widespread corruption, is filing the court challenge on Saturday.
His opposition coalition on Friday said he won 61 percent of the vote, citing figures compiled by the Catholic Church's 40,000 election observers across the vast Central African country. The figures show Tshieskedi received 18 percent, the coalition said.
The church, the rare authority that many Congolese find trustworthy, has said its figures showed a different winner from the one officially declared. In remarks to U.N. Security Council on Friday, the church urged the electoral commission to release its detailed vote results for public scrutiny.
The commission has said Tshisekedi won with 38 percent of the vote while Fayulu received 34 percent.
This could be Congo's first peaceful, democratic transfer of power since independence from Belgium in 1960, but observers have warned that a court challenge could lead to violence. Some Fayulu supporters have worried that the constitutional court could invalidate the results, keeping Kabila in power until a new election.
There are two options, electoral commission president Corneille Nangaa told the Security Council: The official results are accepted or the vote is annulled.
"Even if Tshisekedi's presidency survives these court challenges, he will be compromised beyond repair and reliant on Kabila, whose patronage network controls most of the country's levers of power, including the security forces," professor Pierre Engelbert, a fellow with at the Atlantic Council's Africa Center, wrote on Friday.
The Dec. 30 election came after more than two turbulent years of delays as many Congolese worried that Kabila, in power since 2001, sought a way to stay in office to protect his sprawling assets.
Statements by the international community, including African regional blocs, have not congratulated Tshisekedi, merely taking note of official results and urging against violence.
Congo's 80 million people have been largely peaceful since the vote, though the U.N. peacekeeping mission has reported at least a dozen deaths in protests in Kwilu province, with authorities noting demonstrations in Kisangani and Mbandaka cities.
Internet service has been cut off across the country since election day.
Tshisekedi had not been widely considered the leading candidate. Long in the shadow of his father, the late opposition leader Etienne, he broke away from the opposition's unity candidate, Fayulu, to stand on his own.
After election results were announced, Tshisekedi said Kabila would be an "important partner" in the transition.
Fayulu, who was backed by two popular opposition leaders barred by the government from running, is seen as more of a threat to Kabila's interests.
The difference between Tshisekedi and Fayulu in official results was some 684,000 votes. One million voters were barred from the election at the last minute, with the electoral commission blaming a deadly Ebola virus outbreak. Elsewhere, observers reported numerous problems including malfunctioning voting machines and polling stations that opened hours late.
The presidential inauguration will be on Jan. 22, the electoral commission said Saturday.