Cotu secretary general Francis Atwoli has said he is optimistic of an Azimiola Umoja victory.
Speaking on Tuesday after casting his vote in Khwisero, Kakamega, Atwoli commended the Independent Electoral and Boundaries Commission.
He said they have done an outstanding job.
Atwoli said the process has been smooth despite a few delays.
"I thank the IEBC for stringent measures to deal with any noted malpractice," he said.
"I'm optimistic this is the best, well-arranged election and we will win by a big margin," he said.
The Central Organisation of Trade Unions boss said that he hopes his previous predictions will come to pass. They date back to 2014.
"The whole exercise is good, the returning officers are good and clerical officers are ready to assist ensure sure ballots are put into the required places.
He is among notable leaders who have already cast their votes.
They include Deputy President William Ruto and his running mate Rigathi Gachagua, Azimio presidential running mate Martha Karua and former FirstLady Mama Ngina Kenyatta.
(Edited by V. Graham)
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