Addressing the press at Barons Golf Park in Naivasha, the former NACADA chairman termed the nominations as a sham adding that rigging was part of the day that declared Lee Kinyanjui as the winner.
He will be supporting the re-election of President Uhuru Kenyatta for a second term.
Mututho said he had indicated that he would respect the will of the people during the nominations adding that it was clear they were not free and fair.
“It is clear the party primaries for the county were rigged and marred with irregularities and did not reflect the will of the people,” he said.
According to him, the total votes cast for the gubernatorial seat exceeded those of the senator and women representative saying the figures had been exaggerated.
“You can count the votes and this will tell you the disparities which mean those who voted for the governor did not vote for either the senator or the women representative”.
He accused the incumbent Governor Kinuthia Mbugua and the winner Kinyanjui of massive rigging and bribing voters yet the exercise was to be free and democratic.
“My wife was in the cue in one of the polling stations and some agents of my rivals were giving out Sh1,000 openly, this is why I cannot accept the results of the nominations,” he said.
He said he had a vision for the county adding that should he take over leadership in August he will deliver on the promise of a better, well developed Nakuru.
“When I was campaigning I went to a village where residents have had no development since independence and the poverty levels were alarming,” he said.
He called on Kinyanjui to brace himself for a bruising battle ahead saying the will of the people must be respected and will be reflected in the general election.
Kinyanjui won after defeating incumbent Mbugua with a large margin while Mututho came a distant third.
Mbugua has already contested the election and said he was conducting an audit before deciding on his next move.