In parts of the capital, Nairobi, opposition supporters celebrated into the early hours of Saturday, while others wondered if their investments and businesses might be threatened by the stunning development.
Citing irregularities in how the election commission tallied and reported the Aug. 8 vote, the Supreme Court on Friday declared the results null and void and said a new election must be held within two months.
President Uhuru Kenyatta, who was reelected with 54 percent of the vote, said he would respect the decision, but soon afterward he began publicly condemning the judges for their decision.
"Who even elected you? Were you? We have a problem and we must fix it," he said on live television Saturday, remarks many perceived as a threat against the court.
Opposition leader Raila Odinga, who filed the petition prompting the court's decision, has focused his wrath on the commission supervising the elections, demanding that members be replaced — something most commentators say will not happen before the new elections, opening the way for possible unrest.
"It is going to be a high-octane political campaign season," said political analyst Barrack Muluka, who predicted that Kenyatta would focus on how four judges had robbed millions of their vote while Odinga — who has lost four elections — would focus on a system rigged against him.
"It is going to be a bare-knuckle political fistfight, where the grandiose ideas we had previously are going to be on the back burner, and it's going to be purely name-calling," Muluka said. "The country is likely to be more polarized along ethnic lines."
Like most of Kenya's presidents, Kenyatta is from the Kikuyu tribe, the country's largest, while Odinga is from the Luo, who have felt marginalized since independence in 1963. Voting — and the subsequent violence — often occurs along ethnic lines.
Kenyatta and his Jubilee Party have also positioned themselves as the pro-business force committed to improving the economy, while Odinga's message resonates more with the economically marginalized, such as the Luo, and those fed up with the country's endemic corruption.
For Josphat Ndemo, an artist living in Nairobi's Kibera slum, the court decision was a "victory for justice."
"I never expected it to turn out the way it did," he said, standing next to one of his paintings, showing police storming the neighborhood after last month's election. "Most of us thought it would favor the Jubilee side, and I had very little faith in Kenya's judicial system. This has given us so much hope."
Across the city, however, in the Kangemi market area, businessman Martin Kinyanjui expressed frustration that the country has to redo the election and said he fears that the opposition is just trying to drag the country backward.
"Life had gone back to normal. We are all trying to earn a living and make our lives better," he said in his shop, where he trades secondhand clothes, in a market packed with the Saturday shopping crowd. "We cannot do this the whole year; we have to build the country."
The country's business executives do have reason to dread the elections, explained Joshua Kivuva, a political-science professor at Nairobi University. Kenya's regularly held, competitive elections are very hard on the country.
"The election is the worst thing that can happen to the Kenyan economy; that alone will take two years to recover from," he said, noting that economic growth reliably plummets around election time.
Elections, with their vigorous campaigning, massive spending on bribes for voters and threat of violence, are a time to hold off on making investments and, if possible, move assets outside the country, he explained.
In this case, the country is under even more strain, with a severe drought in the north that has harmed agricultural output and spurred inflation.
While most analysts expect Kenyatta to win the new election, an Odinga victory is possible with his supporters energized by the court ruling. An opposition triumph would mean major disruption in the government, as many of the Kikuyu holding senior posts in the administration would probably be replaced.
"This ethnic switch-over would cause severe paralysis in the state bureaucracy, including delays to licensing, demands for fresh kickbacks, and the risk of contract alteration," warned Robert Besseling, head of Exx Africa, a political risk advisory firm, in a recent report.
In the short term, the biggest flash point will be the Independent Electoral and Boundaries Commission, which oversaw the last election and will probably organize the next one.
Odinga has called for its members to face criminal prosecution, but the president has said they will not be replaced. In any case, with only two months before the election, few think there would be time to find and approve new members.
Besseling, however, warns that Odinga could well organize his followers to engage in social unrest to pressure the government on that point.
Yet despite the strains it will cause, analyst Muluka said the elections are still worth it for the country, in a region with only nominally democratic states such as Rwanda, Uganda and Ethiopia as well as openly repressive ones such as Burundi.
"The country must go through the crucible before it can attain democracy," he said. "Democracy must come at a cost; it is not a walk in the park."
Schemm reported from Addis Ababa, Ethiopia.