EXPLAINER: What you need to know about the high-stakes Ol Kalou by-election

The contest has drawn interest from across the political divide, with major parties seeking to gauge their strength in the politically significant Mt Kenya region.

The ruling United Democratic Alliance (UDA) has fielded Samuel Muchina in a bid to secure the seat, while the Democracy for Citizens Party (DCP) has fronted Sammy Kamau Ngotho, whose candidature has received the backing of former Deputy President Rigathi Gachagua.

Jubilee Party, which previously held the seat, is seeking to retain it through its candidate Wilson Kigwa.

The race has also attracted several other candidates, including Timothy Kamau of the People's Renaissance Movement, Edwin Muchiri of PNU, Stephen Wanyoike of the National Liberal Party (NLP), Edward Mwaniki of the Kenya Moja Movement, Abdifatah Hussein of the Federal Party of Kenya and Rachael Njoroge of the People's Democratic Party.

For UDA, a victory would strengthen President William Ruto's influence in Mt Kenya and reaffirm the party's dominance in a region that played a critical role in the 2022 general election.

For DCP and its allies, the by-election presents an opportunity to demonstrate that Gachagua still commands significant support in the region despite his fallout with the Kenya Kwanza administration.

Jubilee, on the other hand, hopes to prove that it remains a relevant political force in central Kenya.

Ol Kalou has a rich political history. Previous MPs include John Njoroge Muchiri, who served between 2002 and 2007, and Erastus Mureithi, who represented the constituency from 2007 to 2013.

David Kiaraho, who was elected on a Jubilee Party ticket during the 2022 general election, most recently held the seat.

Beyond politics, Ol Kalou is the headquarters of Nyandarua county and one of Kenya's leading agricultural regions.

Farming remains the backbone of the local economy, with residents heavily engaged in the production of potatoes, cabbages, maize and beans, as well as dairy farming and horticulture.

The town has also grown into an important commercial hub, with vibrant wholesale and retail markets linking farmers to consumers in Nairobi and other major urban centres.

Other sectors supporting the local economy include agro-processing, small-scale trade, transport services and construction. The production of building materials such as quarry stones and cabro has contributed to the area's rapid urban growth.

During the campaign period, candidates focused their messages on issues that directly affect residents. Among the key promises made were improvements in road infrastructure, increased support for farmers, job creation for young people and expanded access to education and healthcare services.

The Independent Electoral and Boundaries Commission (IEBC) has since completed preparations for the vote and reminded the constituency's 73,480 registered voters to report to their designated polling stations with either an original national identity card or a valid Kenyan passport.

Voting will take place at 144 polling stations spread across the constituency's five wards of Rurii, Kanjuiri Ridge, Karau, Kaimbaga and Mirangine.

As election day approaches, the commission has issued several warnings aimed at safeguarding the integrity of the poll.

IEBC chairperson Erastus Edung Ethekon has cautioned voters against taking photographs of their marked ballot papers while inside polling booths.

According to Ethekon, the practice violates the secrecy of the ballot and is prohibited under Section 7 of the Elections Offences Act.

"It is against Section 7 of the Elections Offences Act. You shall actually be prosecuted and, if found guilty, you pay a fine of up to Sh1 million," he said.

"We need to tell Kenyans that this matter is very serious. Besides that Sh1 million, the offending party can also be imprisoned for a term not exceeding three years, for a simple act of taking a picture of your vote."

The commission has also warned political parties, candidates and their supporters against wearing party colours or displaying campaign materials at polling stations.

Ethekon noted that the official campaign period ended on July 13 and all participants are required to comply with electoral regulations.

Meanwhile, the Ethics and Anti-Corruption Commission (EACC) has appealed to residents to remain vigilant and report any attempts to influence voters through bribery or other corrupt practices.

EACC Director of Preventive Services Vincent Okongo said the agency is working closely with other institutions to ensure a credible electoral process.

"We appeal to Kenyans to report any form of corruption through our toll-free number 1551. Report such incidents to us as soon as possible so that appropriate action can be taken," he said.

With political parties eager to claim momentum, and voters preparing to make their choice, the Ol Kalou by-election is shaping up to be more than just a contest for a parliamentary seat.

Its outcome is expected to reverberate beyond Nyandarua county and could offer an important glimpse into the political landscape taking shape ahead of the 2027 general election.