The choice of Ms Karua as Azimio-OKA Party presidential candidate running mate has seen some voters change their stand.
The United Democratic Alliance (UDA), which is the most popular party in Nakuru, has lost some of its members who decamped to Azimio coalition moments after Ms Karua was unveiled.
"The choice of Ms Karua has influenced my decision to rethink supporting UDA and I'm now supporting Azimio. I want to make an informed decision," said Ms Dorcas Kendi, a resident of Nakuru Town East.
"The choice of Ms Karua is giving a glimpse of hope to incumbent Lee Kinyanjui who is crisscrossing the county to counter the UDA wave as he fights to consolidate the crucial Kikuyu votes," said Mr George Ouma, a political analyst in the region.
Mr Kinyanjui was among the first leaders to congratulate Ms Karua for her appointment as Mr Odinga’s running mate. He said this was a "sure bet" for Mr Odinga to win the presidential race on August 9.
Mr Kinyanjui, who will be facing his arch-rival Senator Susan Kihika, said the fate of the presidential race has been sealed after the naming of running mates.
"Any observer will tell you that this election was decided on Monday when the top coalitions named their running mates," said Mr Kinyanjui.
Mr Kinyanjui praised the choice of Ms Karua saying, "Ms Karua carries the hopes and aspirations of Mt Kenya region."
Governor Kinyanjui urged Mt Kenya voters who are still undecided or are supporting UDA to rethink their stand ahead of August 9 polls.
In an apparent criticism of the UDA economic forums that are being held across the country by the Kenya Kwanza coalition, Mr Kinyanjui said:
"We're not interested in long economic debates by the same team that brought it down. Kenyans need a clean and efficient government that cares for its people."
Azimio presidential candidate
Many political analysts in Nakuru believe that if Governor Kinyanjui succeeds in convincing voters to support Azimio presidential candidate, this could boost Mr Odinga's numbers.
"The Kikuyu vote remains the battleground and if Governor Kinyanjui continues to dig in and convince those in UDA to decamp in the coming days, it will be a big win for Azimio presidential candidate," said Mr Benson Rubia, a resident of Nakuru Town West.
The latest statistics from IEBC indicate that 58 per cent of Nakuru voters are from the populous Kikuyu community, 24 per cent are Kalenjin and 18 per cent are from minority communities.
This loosely means that at least 650,000 voters are Kikuyus, 264,000 are Kalenjins and about 200,000 are minority groups.
However, a resident of Kuresoi North said that the ground is slowly shifting, and it will not have a big impact on the presidential and gubernatorial races.
"Ms Kihika is still the woman to beat on August 9. Those who are thinking Governor Kinyanjui can turn the tables are something between a dream and a miracle," said Mr Alfred Rono, a resident of Kuresoi North.
Both Mr Kinyanjui and Ms Kihika have intensified their campaigns in an election that could either usher in the first woman governor or see the incumbent retain his seat.