Kanu and Jubilee Party are set to battle it out for the Wajir West parliamentary seat on Thursday.
The contest pits Kanu's Ibrahim Mohammed against Jubilee's Ahmed Kolosh, in what has been interpreted in some quarters as a battle between Rift Valley political bigwigs Deputy President William Ruto and Baringo Senator Gideon Moi.
The seat fell vacant after the Supreme Court nullified Mr Kolosh's election over irregularities at the Qara polling station.
Mr Kolosh, who had run on an ODM ticket, decamped to Jubilee and was welcomed by the DP.
Dr Ruto's hand was also seen in the withdrawal of the ODM candidate for the seat, Prof Mohamed Elmy.
Mr Ali Noor Abdi of Labour Party of Kenya and Agano Party's Abass Nunow Shihaw also quit the race after meeting Dr Ruto in Nairobi.
But although the three candidates pulled out, their names are still on ballot papers.
Both the DP and Mr Moi have been fighting for control of the vote-rich Rift Valley for use as a base for their bids for the presidency in 2022.
While ODM won most of the seats in the former northern Kenya in 2013, it was given a run for its money by Jubilee in 2017, with the latter taking control of Wajir, Mandera, Marsabit, Garissa and Isiolo counties.
Wajir West constituency has 27,444 registered voters, according to the latest statistics by the Independent Electoral and Boundaries Commission (IEBC).
The electoral agency has set up more than 10 mobile polling stations, amid fears of a low turnout due to the drought, which has forced many families to move from their homes.
During a press briefing at the Griftu Pastoralist Training Centre, which will serve as the tallying centre, IEBC officials said everything was set for the by-election.
"Voters will be required to cast their ballots at the polling stations where they registered in the past general election," Returning Officer Maurice Raria said.
"We have communicated the same to agents and candidates so that voters stick to their polling stations."
Mr Raria pointed out that they will not transmit the results from the polling stations, but tally the votes at the centre.
The poll officials will use the Kenya Integrated Management System (Kiems) to identify voters, he said.
But the area has poor network connectivity, which might interfere with the kits' efficiency.
IEBC boss Wafula Chebukati said the commission had noted a decline in the voter turnout during mini polls, as witnessed during the by-elections in Ugenya and Embakasi South on April 5.
But he assured that the commission will conduct a free and fair election, which will leave all parties satisfied with the outcome.
"In fact, they (election officials) were not aware of where they would be deployed until yesterday, when they were dispatched to the polling centres and polling stations alongside voting materials," he said. "I am satisfied with the level of preparedness."
Regarding security, Mr Chebukati noted that no incidents were reported during the two-month campaign period.
Voting materials were distributed to the 75 polling stations in the vast constituency.