The nullification of Dr Alfred Mutua's August 8 gubernatorial victory caught scores of Kenyans by surprise.
A Court of Appeal judge ruled that Mutua's win could not meet the constitutional threshold of verifiability, warranting its nullification.
Kenyans have been reacting variously to the dramatic development.
Garissa residents have also weighed in on the annulment.
Here are some of their reactions:
"To be honest, I did not see it coming. I thought that the Court of Appeal would uphold his win," Mustapha Karim said.
"The people of Machakos will have the final decision," Saumu Omar said.
"If the constitutional threshold was not met, then the decision to nullify it is the right one, Kamal Kuno said.
"I am happy for Wavinya Ndeti. I hope she wins the by-election," Jasmine Mohamed said.
"This is another cost that will be borne by the taxpayer. I do not support the ruling," Samin Galgalo said.
"Kenyans are tired. Stop subjecting them to elections," Garbo Jumo said.
"We are a country that has the rule of law. Let's respect it," Amina Sure said.
"A High Court upheld his victory. What's wrong with our courts," Sule Hukhe said.