Bomet Governor Isaac Ruto, Kakamega Senator Boni Khalwale, and Budalang'i MP Ababu Namwamba are among the casualties in this year's highly competitive election.
Provisional results from IEBC show Ruto, who is also the Chama Cha Mashinani party leader, with 83,601 votes against National Assembly Deputy Speaker Joyce Laboso's 172,389.
The governor's decision to cross over to the National Super Alliance (NASA) as one of its co-principals appears to have cost him his seat, making Laboso to be one of the first women county bosses in the country.
Kakamega Governor Wycliffe Oparanya appeared to enjoy a convincing lead with 370,855 votes, representing 70.40 per cent of the votes cast, against Senator Khalwale's (Ford-Kenya) 130,343 votes, translating to 24.74 per cent.