Thousands of celebrators flocked to the rundown opposition headquarters of the Union for Democratic and Social Progress, whose candidate Felix Tshisekedi was proclaimed winner of Congo’s presidential election in the wee hours of Thursday morning. His win, in a country yet to experience a democratic transfer of power, was seen by some as a new dawn.

But on the other side of Congo’s sprawling capital, Kinshasa, another opposition candidate who had been heavily favored in pre-election polls and tallies conducted by election observers called the results “an unacceptable electoral fraud.”

Martin Fayulu was calm but aggrieved when he addressed the press and urged the largest election observer mission to “reveal to the Congolese people the name of the person who truly incarnated the choice of our people.”

In a statement, he described the results as an “electoral hold up” that didn’t reflect the ballots and called on people to “rise as one man to protect victory.”

The observer mission, run by Congo’s powerful Catholic church and known as CENCO, was due to hold a news conference on Thursday afternoon. It wasn’t immediately clear whether they planned to release their own tallies showing Fayulu as the election’s winner.

A discrediting of the election by CENCO could ignite outrage among supporters of Fayulu’s coalition as well as isolate Congo further from an already-skeptical international community. Fayulu and other losing candidates are entitled to appeal the election results.

Voices of doubt were starting to trickle in from outside Congo by Thursday morning.

“We must have clarity on these results, which are the opposite to what we expected,” French Foreign Minister Jean-Yves Le Drian told French media. “The Catholic Church of Congo did its tally and announced completely different results.”

Government spokesman Lambert Mende retorted that the French should keep out of the election.

“France has nothing to do with the vote in the Congo and if Mr. Le Drien thinks Congo is a province or colony of France, he just needs to name the president of Congo.”

The vote was marked by widespread irregularities. In its final report, CENCO said 38 percent of polling stations it observed were missing materials at the start of Election Day, and that in hundreds of cases, ballot boxes were not sealed before counting and polling stations did not properly verify voters’ identities.

A separate domestic observer mission called SYMOCEL said it witnessed 52 major irregularities, including physical tampering with results, in the 101 vote-counting centers it monitored. There were 179 such compilation centers across Congo.

The electoral commission also cited an ongoing Ebola outbreak in postponing voting in the eastern cities of Beni and Butembo, effectively barring more than a million people from the presidential vote in areas that were expected to heavily back Fayulu. The difference in the number of votes received between Tshisekedi and Fayulu countrywide was smaller than the registered voting populations in those two cities.