But in its ruling, the court found that senior poll officials had not followed electoral procedures properly to ensure a credible vote. It was the first time in Africa that a court had nullified the election of an incumbent.
For weeks since the court ruling, Mr. Odinga has demanded that senior poll officials be replaced and prosecuted. He has also called for the replacement of the companies in charge of printing ballot papers and providing the devices needed for the electronic transmission of results, areas that the court found to have been flawed.
Western diplomats have criticized Mr. Odinga for making too many demands, which could have the effect of undermining confidence in the electoral commission’s ability to hold the new vote. Mr. Odinga has called for protests to take place until the commission makes the changes he seeks.
On Wednesday, hundreds of his supporters demonstrated in Nairobi, the capital, and in some opposition strongholds around the country, demanding the resignation of senior election officials.
“Can you go into an election with the same cooks who poisoned your food?” said Janet Ongera, an opposition lawmaker from Kisii, a city in western Kenya.
“This will add even more sulfuric acid,” Ms. Ongera added. “What we want is a level playing field.”
Since the Supreme Court’s ruling in September, Mr. Odinga and Mr. Kenyatta, along with the electoral commission, have failed to reach an agreement on how to conduct the new election.
Analysts say that with shrinking campaign funds and worries of eroding support, Mr. Odinga was most likely playing for time by withdrawing from the race.
Mr. Odinga appeared to be pushing for a later date for the new election, based on his interpretation of a 2013 ruling that calls for a new vote to take place within 90 days if a candidate suddenly dies. An extended campaign would give the authorities more time to make the electoral changes sought by Mr. Odinga.
Earlier in the day, before the election commission’s decision, Kenya’s Parliament passed a set of amendments to the electoral law that seemed intended to ensure a victory by Mr. Kenyatta. One measure said that in an election or runoff with only two candidates, if one withdraws, the other would be automatically declared the winner.
Another amendment would bar the Supreme Court from nullifying a presidential election unless violations of the Constitution or electoral law significantly altered the outcome.
That measure was widely criticized as an attempt by the government to clip the judiciary’s wings. Although the parliamentary vote was boycotted by opposition lawmakers, it passed with the support of Mr. Kenyatta’s party.