The impoverished but mineral-rich central African nation held four concurrent elections on Wednesday to pick a president, national and regional lawmakers and local councillors.
President Felix, 60, is running for a second term in office against a backdrop of years of economic growth but little job creation and soaring inflation.
The vote on Wednesday was marked by massive delays nationwide, with the electoral commission still attempting to deliver materials to voting stations long after polls were meant to have opened.
In some cases, polling stations never opened.
Denis Kadima, the head of the electoral commission, declared on national television on Wednesday night that people in places where casting ballots proved impossible would vote on Thursday.
On Thursday morning, voting had started in several areas in the conflict-torn east, according to AFP reporters.
"Everything is going well, electoral operations started at 6 am" (0400 GMT), said Likanga Ikoba, a local official in the Walikale area of North Kivu, via telephone.
Amini Mumbere, another local official, said that two villages in the Lubero territory were also voting.
It was not clear how many polling booths are open on Thursday.
Addressing reporters on Wednesday, electoral commission chief Kadima said the problems were spread across the vast country's 26 provinces.
He also estimated that 70% of voters had been able to cast ballots.
The DRC is one of the poorest countries in the world despite its vast reserves of copper, cobalt and gold.
Around 44 million Congolese in the nation of 100 million are registered to vote, and more than 100,000 candidates are running for various positions.
Initial results are expected by December 31. The Constitutional Court is then expected to announce definitive results on January 10.
Logistical problems
Staging elections in a country roughly the size of continental western Europe, with very few roads, posed a daunting logistical challenge.
There had long been concerns that the electoral commission was unprepared, which proved valid on polling day.
By Wednesday afternoon, an influential election observer mission by a union of Congolese Catholic and Protestant churches indicated the scale of the voting problems.
Nearly a third of polling booths in the country had not opened, the observers said, and about 45% of voting machines suffered technical problems.
There was little sympathy from leading opposition politicians, who described the process as chaotic.
The main opposition candidates — gynecologist Denis Mukwege, 68, the 2018 Nobel Peace Prize laureate; 58-year-old business magnate and ex-provincial governor Moise Katumbi; and 67-year-old ex-oil executive Martin Fayulu — all complained of irregularities.
Five opposition presidential candidates, including Fayulu and Mukwege, later rejected the vote extension, arguing that it was illegal.
In a joint statement, they called for fresh elections.
Violence in the east
Armed conflict in eastern DRC also overshadowed much of the electoral campaign.
Militias have plagued the troubled region for decades, a legacy of regional wars that flared in the 1990s and 2000s.
Tensions have ratcheted up further since the M23 group began capturing swathes of territory in late 2021.
Rwanda has been accused of supporting the rebels, which Kigali denies.
Clashes with M23 fighters have subsided in recent weeks but they continue to hold sway over large parts of North Kivu province, where voting was impossible.
Forum