Throughout his campaign, Mr. Odinga told supporters the election was rigged. He has said he was robbed of victory in the previous two contests. In 2013, Mr. Kenyatta won by a tiny margin, prompting Mr. Odinga to ask the Supreme Court to invalidate the election.
Mr. Odinga has called on his supporters to remain calm, but at a news conference on Wednesday he also said, “I don’t control the people.”
At the same news conference, Mr. Odinga’s running mate, Kalonzo Musyoka, issued what seemed to be a call for supporters to go out into the streets when they were given a signal. “There may come a time when we need to call you into action,” he said.
Andrew Limo, a spokesman for the Independent Electoral and Boundaries Commission, rejected Mr. Odinga’s latest claims. “The results come from the election management body,” he said by telephone. “They cannot come from a candidate or party.”
International observers have widely applauded the electoral commission’s conduct, and note that the official results are based on paper ballots tallied and verified at polling stations, not those transmitted electronically.
There has been no evidence so far that votes have been tampered with at polling stations or that the results contradict reports from party agents present during the counting of ballots, said John Kerry, the former United States secretary of state and an election observer for the Carter Center.
“So obviously there is a moment of reckoning coming up pretty soon,” he said in a telephone interview. “And the reckoning will be based on a paper trail.”
The electoral commission has already received nearly all documents detailing the results from each polling station, Mr. Kerry said. “The process is very meticulous and, plus, all the parties have copies of the documents,” he said. “So there is a huge trail of documentation. All of that will ultimately give confidence to people that they can trust in the outcome of the vote.”
Another top Western observer, speaking on the condition of anonymity because observers do not want to be seen as interfering, cast doubt on Mr. Odinga’s assertions. She said she had seen no evidence of vote-rigging.
The new claims by the opposition came a day after Mr. Odinga said that election commission servers had been hacked to award Mr. Kenyatta a 10-point lead. Mr. Odinga described the 2017 election a “fraud.”
The hackers, he told reporters earlier this…