The Jubilee Party strongholds of central Kenya and Rift Valley will see political heavyweights face off in high-stakes primaries on Friday.
After polling in 21 counties, high-flying politicians may go into political oblivion in regions where the ruling party's ticket is as good as a win.
And even with the electoral commission having left open a window for nominations losers to run as independent candidates, that may not improve their chances.
"We do not want to say that because you are the incumbent you should win our nominations," said Jubilee Party Secretary-General Raphael Tuju.
After the primaries in 45 counties -- as western and north-eastern Kenya, and Coast and Nyanza carry out theirs on Tuesday -- 6,255 of the 8,012 aspirants will be thrown out, which the party says will be the height of democracy.
The primaries are a delicate balancing act for President Uhuru Kenyatta and his deputy William Ruto, amid fears that backing a candidate may cause a fallout suicidal for their re-election.
"All of the aspirants are my friends," said President Kenyatta during a tour of his home county of Kiambu. "And I have said I will not interfere. Whoever is elected is the one we will work with."
In the county, his closest friend, Governor William Kabogo, and Kabete Member of Parliament Ferdinand Waititu are waging the battle of their lives to bag Jubilee's gubernatorial ticket, which will mean getting the Head of State's support in the General Election.
So fierce is the battle in 17 strongholds, as well as Nairobi, that the party rescinded polling centre mergers.
At nine, Nandi has the most governor aspirants. Nyandarua follows with seven and Kirinyaga five.
In Nairobi, Senator Mike Sonko will be up against 2013 presidential candidate Peter Kenneth and former Starehe MP Margaret Wanjiru for the top county job.
Murang'a Governor Mwangi wa Iria will go head-to-head with Kigumo MP Jamleck Kamau as his Kirinyaga counterpart Joseph Ndathi faces former powerful Devolution Cabinet Secretary Anne Waiguru. Nakuru Governor Kinuthia Mbugua faces his 2013 challenger Lee Kinyanjui and former Naivasha MP John Mututho.
Embu could elect its first woman governor -- even the country's first -- should Runyenjes MP Cecily Mbarire trounce incumbent Martin Wambora.
In Bomet, the National Assembly Deputy Speaker, Dr Joyce Laboso, will run against former Konoin MP Julius Kones as Kericho Governor Paul Chepkwony battles Ainamoi MP Benjamin Lang'at and Mr Fred Kirui.
Former Cabinet ministers Henry Kosgey and Felix Koskei are among eight seeking to topple the Nandi governor, Dr Cleophas Lagat, while Uasin Gishu Governor Jackson Mandago will be up against billionaire businessman Zedekiah 'Buzeki' Bundotich.
In Laikipia, former Foreign Affairs permanent secretary Thuita Mwangi is eyeing Governor Joshua Irungu's seat as Nyandarua Governor Daniel Waithaka battles former Head of Public Service and Secretary to the Cabinet Francis Kimemia and five others.
Nyeri Governor Samwel Wamathai, who took over last month following the death of Nderitu Gachagua, is being challenged by Senator Mutahi Kagwe, former Vision 2030 director Wahome Gakuru, hotelier Patrick Munene, Athi Water Services Board chairman Wachira Keen and Mr Cocorico Kinyanjui.
Nandi also leads in Senate aspirants -- 15, with Uasin Gishu having 14, Laikipia 10 and Bomet nine.
In the National Assembly races, Turbo Constituency leads the pack with 18 aspirants, neighbouring Soy has 17, followed by Bomet East (16), Sotik and Keiyo South, both at 13, with Kigumo in Murang'a having 12.