Ms Ong'era has already established herself as a heavyweight in local and national politics.
During the last General Election, Ms Ong'era, an advocate, won against 11 other candidates, who included the incumbent Sally Otara. Ms Otara is now supporting her.
The legislator says she has executed her mandate well.
"We have seen the community accommodating women venturing into politics in recent years and that is a step in the right direction bearing in mind that women too are good leaders," she says.
Ms Ong'era is also counting on her development record, saying she has initiated several projects in the last five years.
"Some of them are complete. I'm seeking another term so I can complete the rest. And it's not just about the ongoing projects, I have more plans for the county. For instance, my office has been looking into the issues affecting youth, women, the needy, and the disabled in our society. I have a plan to attend to the needs of these groups."
After the 2013 election, Ms Ong'era was appointed ODM executive director and later earned a nomination slot to the Senate, where she serves as Minority Deputy Whip. She is also a member of the Kenyan Delegation to the Pan African Parliament.
She also played key roles in both the 2005 and 2010 referendums.
Before changing her mind to run for the seat, Ms Otundo had her sights on the governorship. However, her running mate dropped out of the race, forcing the aspirant to change her course.
Ms Otundo is calling on political parties to support women politicians whom she said have limited resources.
"It is not easy for us. Sometimes, women win only because they are in particular political parties."
For Ms Donya, this will be her second attempt to capture the seat after failing in 2017.
"We need to change the way we do things. I want to change the way we manage and use the National Government Affirmative Action Fund to ensure every deserving cases are reached by the fund," she says.
Ms Onsarigo, who served as a county CEC during Governor James Ongwae's first term in office, and Ms Bwari, a teacher who was an official with the Kenya National Union of Teachers, are making heir first attempt.
"My priority will be empowering needy families and ensuring equitable distribution of resources including bursaries," says Ms Bwari.
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Other first-time candidates are Ms Oroo, the widow to the former MP Bonchari Oroo Oyioka, Ms Onderi, Ms Nyamao and Ms Karani.