The Democratic Republic of Congo voted Sunday for a successor to long-serving President Joseph Kabila after a tense campaign the opposition said was marred by crackdowns and disruptions.

Kabila’s handpicked successor, Emmanuel Ramazani Shadary, is running for the ruling coalition and faces strong challenges from opposition alliances headed by Felix Tshisekedi and Martin Fayulu. The current president, in power for almost 18 years, is barred by the constitution from running for a third term, having won elections in 2006 and 2011. Voters will also select national and provincial lawmakers.

“This is going to be a historic vote,” Martin Mudiayi, a shop attendant, said as he waited for his turn to vote in a polling station in the eastern city of Goma. “The time has come for President Kabila and his group to step down and give a chance to a new leadership.”

Congo, Africa’s biggest copper producer and a key source of minerals essential to the smartphone and electric-vehicle industries, could be on the verge of its first transition of power through the ballot box since independence in 1960. Despite the presence of more than 16,000 United Nations peacekeepers in the vast central African country, the government took the unusual step to refuse logistical support from the UN and financial assistance from international donors to organize the vote. It also barred some foreign observers, including the European Union.

“We committed to financing our electoral process entirely ourselves for the very first time in our history,” Kabila said on state TV late Saturday. “For us, it’s an effort to shield our country from foreign interference liable to thwart the will of self-determination of our people.”

Warehouse Fire

The opposition accuses the electoral commission, known as CENI, of preparing an election that’ll be neither free nor fair, citing several incidents that occurred in the run-up to a vote that was already two years overdue. The commission pushed back the polls by another seven days from Dec. 23, blaming a fire at one of its warehouses in the capital, Kinshasa, and also suspended campaigning three days early in the city as Fayulu was planning a mass meeting.

The authority then postponed elections in three parts of the country until March, citing an Ebola outbreak, militia attacks and inter-communal violence. That effectively disenfranchised 1.2 million of Congo’s 40 million registered voters in regions known as strongholds of Kabila’s critics. Health Minister Oly Ilunga previously said the virus wouldn’t hinder elections.

The commission has also been criticized for importing tens of thousands of touchscreen voting machines from South Korea. While it said casting a ballot should take 90 seconds per person, scores of voters in Kinshasa and Goma said they took much longer, raising concerns voting could extend beyond the official 5 p.m. closing time.

“I’m used to using the internet so it took me two or three minutes,” said Jules Kabayu, who voted in a northwestern neighborhood of Kinshasa. “Many others are not used to it and you must explain to them what they must do.”

Numerous problems were noted by the local Catholic Church, which deployed thousands of observers throughout the country. Observers were barred from entering polling stations, hundreds of voting machines didn’t work properly and there were cases of vote-buying and vandalism, according to a statement. In Limete, an opposition stronghold in Kinshasa, two polling centers opened almost eight hours late because voter rolls were missing.

“They don’t want us to vote, that’s why they’ve created this scam,” said pensioner Ivon Lulendo as he sat waiting outside the center.

Tshisekedi, the leader of Congo’s largest opposition party, has teamed up with Vital Kamerhe, who heads another major party and came third in 2011’s election, while Fayulu is boosted by the support of heavyweights Jean-Pierre Bemba and Moise Katumbi.

‘Deeply Worried’

The opposition has also accused the Congolese state of hampering their campaigns while aiding Shadary’s. At least seven of Fayulu and Tshisekedi’s supporters were killed and many more wounded by security forces from Dec. 9 to 13 as they gathered for rallies in various parts of the country, according to New York-based Human Rights Watch.

The United Nations High Commissioner for Human Rights Michelle Bachelet said she was “deeply worried about the reports of excessive use of force, including live ammunition, by security forces against opposition rallies.”

Two recent polls published by New York University’s Congo Research Group record Shadary as trailing the opposition by a large margin, with Tshisekedi topping a survey in October and Fayulu leading a second published Dec. 28.

Provisional results of the presidential contest are due to be announced Jan. 6 and the final decision on Jan. 15. The next head of state is scheduled to be sworn in three days later.