The church, a powerful voice in the heavily Catholic nation, deployed some 40,000 electoral observers but could not say who the clear winner appeared to be, as Congo's electoral regulations forbid anyone but the electoral commission to announce results.
Observers have reported multiple irregularities as the vast, mineral-rich Central African country voted for a successor to departing President Joseph Kabila. This could be its first peaceful, democratic transfer of power since independence from Belgium in 1960.
The ruling party loyalist whom Kabila put forward as his preferred successor, Emmanuel Ramazani Shadary, already has said he expected to win, while polling before the election had top opposition candidate Martin Fayulu ahead.
The electoral commission's president said it had collected results from about 20 percent of polling stations, while some Congolese expressed doubt that the first results would be released on Sunday as expected.
"We are working hard to announce them as soon as possible," Corneille Nangaa said. The internet remained blocked in the country in an apparent attempt by the government to calm speculation about the results.
The United States urged Congo to release accurate results and restore internet access, warning that those who undermine the democratic process could face U.S. sanctions. The State Department noted the reported troubles on election day and said results should be compiled transparently, with observers present, so that the votes of millions of people "were not cast in vain."
The internet outage has hampered the election observers' work. No Western election observers were invited to watch the vote, which was meant to occur in late 2016, after Congo's government was annoyed at international pressure amid concerns that Kabila was trying to stay in power.
"The decision to cut internet and text messages hampered the transmission of data from the field," said Cyrille Ebotoko, technical supervisor of the Catholic church's observer mission. "It delayed our work by three days and considerably increased the cost since everything had to be done by phone."
Thirty-eight percent of the some 40,000 polling stations the mission observed were still missing electoral materials more than three hours after polls opened on Sunday, the mission said. And 23 percent of its observers' reports noted that voting had to be suspended at some point because of troubles with voting machines.
Overall, however, the irregularities did not considerably impact the voting, said Father Donatien Nshole, secretary-general of the church organization known as CENCO. Shadary, a former interior minister, is under European Union sanctions for a crackdown on Congolese who protested the delayed election. Kabila, blocked from serving three consecutive terms, has hinted he'll run again in 2023, leading the opposition to suspect he'll wield power behind the scenes until then to protect his vast wealth.
The other leading candidates were Fayulu, a businessman and lawmaker in Kinshasa, and Felix Tshisekedi, son of late opposition icon Etienne and head of Congo's most prominent opposition party. Some 1 million of Congo's 40 million registered voters were barred from Sunday's election at the last minute as the electoral commission blamed a deadly Ebola virus outbreak in the east. Affected people in Beni and Butembo cities protested as some observers warned that not allowing them to vote undermined the credibility of the election.
The cities' residents can vote in March, months after Congo's new president is set to be inaugurated on Jan. 18. Election day was largely calm. Life in the capital, Kinshasa, had returned to near-normal on Thursday, though some residents expressed frustration at the internet outage.
"We are waiting and trying to adapt, searching for places where we can still find network because we need it to work," businessman Paul Odimba said. "I can understand the government's decision because fake news was spread indeed, but some of us that are impacted are able to make the difference between fake and real news."
Associated Press writer Matthew Lee in Washington contributed.
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