ONCE AGAIN a poorly run election in a volatile African country threatens an explosion of bloodshed. The setting this time is particularly concerning: Congo, a country nearly the size of Western Europe, with a population of more than 70 million — and a history of civil war that killed millions between 1997 and 2002. An election Nov. 28 pitted the incumbent president, Joseph Kabila, against a 78-year-old populist icon, Étienne Tshisekedi. Poor organization, violence and attempts at manipulation made both the vote and the subsequent count a mess. On Friday, Mr. Kabila was declared the winner, but Mr. Tshisekedi refused to accept the result, and some of his supporters clashed with security forces in the capital, Kinshasa. Though an uneasy calm prevailed Sunday, Congo’s neighbors, the United Nations and outside parties such as the United States will have to keep working to prevent a crisis.

Residents of Kinshasa, a city of 10 million, have been bracing for trouble ever since preliminary returns showed Mr. Kabila with a wide lead in what was expected to be a close contest. Final results gave the president 49 percent, to 32 percent for Mr. Tshisekedi in a field of 11 candidates. Observers from the Carter Center said that the official results “lack credibility,” reporting that there was improbably high turnout in areas where Mr. Kabila is strong and that thousands of polling stations in Kinshasa, an opposition stronghold, had not been counted. Mr. Tshisekedi has been claiming he won since Election Day.

One way to defuse the standoff is for outside powers to insist on greater transparency. Congolese law requires that vote totals be reported from each of some 60,000 polling stations, which would allow them to be checked against the tallies of observers at the stations. A full report that matches observer counts and confirms a victory by Mr. Kabila could put pressure on Mr. Tshisekedi to refrain from mobilizing street rallies. The Obama administration and the European Union appropriately have been pushing for “accurate and timely publication of vote counts by polling station,” as a State Department statement put it.

Mr. Tshisekedi had promised that his followers’ reaction to a loss would mimic the Arab Spring revolts in northern Africa. More likely, the result of taking to the streets would be a bloody contest like those that followed disputed elections in Kenya and Ivory Coast. At worst, Congo’s multi-sided, transcontinental war could reignite. The United Nations, which has 19,000 troops in Congo, should be prepared to act quickly to prevent a broader conflict, while Western governments and Congo’s neighbors should make clear to Mr. Kabila that excesses by his security forces will not be tolerated. Congo’s election is already a political failure; the challenge now is to prevent it from triggering a humanitarian catastrophe.