Deputy President William Ruto will confront an enormous hurdle that could propel or break his presidential bid as primaries get underway.
Ruto has maintained strong support from President Uhuru Kenyatta's Mt Kenya backyard but chaotic primaries on Thursday in the countrywide balloting could jolt his fortunes.
Four thousand hopefuls will be running in Rift Valley and 2,000 elsewhere, totalling 6,000 countrywide.
In the past, many primaries have been chaotic, filled with rivalry and violence but DP Ruto has focused on democracy and persuaded some rivals to drop out.
He has said the losers with the most votes will get seats in his government if he forms it.
Some of the counties that will experience tough primaries include Uasin Gishu, Kiambu, Kericho, Bomet, Baringo and Elgeyo Marakwet counties.
