Laikipia Governor Ndiritu Muriithi (Jubilee) was also behind his predecessor Joshua Wakahora.
"We are confident of a Raila Odinga win," said Mr Muriithi, avoiding comments on his own race. "Our agents tallies are showing Raila will hit the 52 per cent mark at the end of this exercise."
But former Cabinet Secretary Mwangi Kiunjuri (The Service Party of Kenya) appeared poised to reclaim his Laikipia East parliamentary seat, with tallies showing him with a slight edge over the incumbent Mohamed Amin Deddy of UDA. He, however, said he would only speak after IEBC announced the results.
In Kieni, Nyeri, the Jubilee Party Director of Elections Kanini Kega remained cautious even as early results showed he was behind UDA's Njoroge Wainaina.
"Opening another chapter, when one door closes, another one opens. Heading to Bomas," posted the MP on social media.
In Murang'a, almost all elective positions appeared likely to be taken by UDA candidates.
The party allies had already started celebrating the provisional results as they camped at constituencies tallying centres waiting for official communication.
By evening, preliminary results showed Senator Irungu Kang'ata in the lead with 146,030 votes against Jubilee Party's Jamleck Kamau, who had 52,736 votes in the race for the governor's seat.
In the senatorial race, Joe Nyutu had 196,926 votes against Kembi Gitura's 43,580 votes.
In Mathioya, Dr Edwin Mugo had by mid-day garnered 20,911 votes against the incumbent Peter Kimari, who had 8,684 votes.
Kandara MP Alice Wahome (UDA) was also on a path to victory with 22,929 votes, ahead of Chege Njuguna, who had recorded 12,313 votes.
In Kigumo, Joseph Munyoro (UDA) took an early lead after he polled 24,270 while the outgoing MP Wangari Mwaniki had 7,548 votes. Former CAS Zack Kinuthia had polled 8,537 votes.
Provisional results from Kangema also showed Peter Kihungi of UDA with 19,665 and George Kibuku of Jubilee 7,692 votes.
In Kiharu, Ndindi Nyoro appeared set to secured a second term in Parliament with preliminary results showing he had 68,434 votes against his rival Karanja Wamatangi's 9,256.
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Among those who conceded defeat yesterday were former Mukurwe-ini MP Kabando Kabando, who was in the Nyeri gubernatorial race, former Assistant minister Kilemi Mwiria in the Tigania West contest and MC Jessy in South Imenti.
[Reports by Wainaina Ndung'u, Nderitu Gichure, Phares Mutembei and Boniface Gikandi]