The result will undercut Tshisekedi's ability to deliver on campaign promises to make a break with the 18-year Kabila era and fuel suspicion that his victory, announced on Thursday, came through a backroom deal that will preserve Kabila's influence over important ministries and the security forces.
Kabila is due to step down in the coming days after 18 years in power, in what was meant to be Congo's first democratic transfer of power in 59 years of independence. But he has signalled he intends to remain involved in politics and might run for president in 2023 when term limits no longer apply.
Lawyers for the runner-up in the presidential election, Martin Fayulu, were on their way to Congo's highest court on Saturday to file a fraud complaint.
Fayulu says he won in a landslide with more than 60 percent of votes, and accuses Tshisekedi of striking a deal with Kabila to be declared the winner.
Late in the morning, about 50 Republican Guard soldiers and police officers surrounded his residence, sending dozens of his supporters, who had been chanting against Kabila and Tshisekedi, fleeing inside, a Reuters witness said.
Tshisekedi's camp denies that there was any deal with Kabila and says meetings it held with the president's representatives after the election were meant solely to ensure a peaceful transfer of power.
LITTLE ROOM FOR MANOEUVRE
Either way, the parliamentary majority retained by the handful of parties in Kabila's coalition will curtail Tshisekedi's room for manoeuvre. Under the constitution, the majority enjoys significant powers and the president must appoint his prime minister from its ranks.
The prime minister, in turn, must countersign presidential orders appointing or dismissing military chiefs, judges and heads of state-owned enterprises.
Adam Chalwe, a national secretary for Kabila's PPRD party, the biggest within the FCC coalition, told Reuters that results from the individual races announced by the electoral commission (CENI) early Saturday morning showed FCC candidates taking more than 300 out of 500 seats in the National Assembly.
Reuters was not immediately able to confirm that independently.
Parties in the FCC coalition accounted for about 350 seats in the previous legislature.
The coalition's presidential candidate in the Dec. 30 election, Emmanuel Ramazani Shadary, finished a distant third with 24 percent of the vote. Pre-election polling had shown the FCC lagging behind opposition parties in legislative races.
In a tweet on Saturday, Fayulu wrote that CENI's results "were invented out of whole cloth. I demand a hand recount of all votes for the three elections (presidential, national legislative and provincial)".
The disputed outcome threatens to reawaken violence in the huge and tumultuous central African country where millions have died during civil wars since the 1990s.
Security forces killed dozens who protested at Kabila's refusal to step down when his official mandate expired in 2016, and militia violence rose across the country as armed groups moved to fill a perceived power vacuum. (Additional reporting and writing by Aaron Ross, Editing by Ros Russell/Mark Heinrich)
(This story has not been edited by Devdiscourse staff and is auto-generated from a syndicated feed.)