Party says Mr Odinga will soon visit the county to campaign for Ochillo Ayacko.
Opposition leader Raila Odinga will only support ODM candidate Ochillo Ayacko in the Migori senatorial by-election, the party has said.
In a statement posted on Twitter on Sunday, the Orange party said Mr Odinga would soon visit the county to campaign for the party candidate ahead of the October 8 by-election.
The party added that it is not bothered by aspirants from other parties who have been using Mr Odinga’s name in their campaigns, saying they will not succeed in swaying voters.
“In Migori, the Party has only one candidate who is Dr Ochillo Ayacko. He is the candidate Raila Odinga supports and will be campaigning for. Anybody else using the party leader's name or any of his nicknames known to his supporters to attract attention will not succeed,” the party said.
The seat fell vacant following the death of Mr Ben Oluoch Okello, who succumbed to throat cancer at a Nairobi hospital in June.
Migori ODM chairman Philip Makabong’o had recently threatened to sue Mr Ayacko’s rivals for publishing posters and billboards with the word ‘Baba’.
Federal Party of Kenya candidate Eddy Gicheru Oketch has erected several billboards within Migori town with words “Wan the wan jokababa (All of us are Baba’s children)”.
Mr Peter Jobando, the Green Congress of Kenya candidate, has also designed his posters with the name ‘baba’ inscribed next to his initials.
Meanwhile, the killing of Rongo University student Sharon Otieno has added a twist to the senate seat race, with leaders allied to ODM using the incident to castigate Mr Obado, who had declared his opposition to Mr Ayacko’s candidature after the Orange party handed him a direct ticket.
Mr Obado shifted his support to Mr Oketch after former MP Dalmas Otieno withdrew from the race.
Mr Oketch's supporters have complained that ODM politicians from the county are using Ms Otieno’s killing as a campaign tool.
"It's true the incident is a major setback to our campaigns because Mr Obado will now concentrate on clearing his name and it's true he has lost some moral ground," said an ally of Mr Oketch, who asked not to be named because of the sensitivity of the matter.
"We were really banking on his massive grassroots networks and of course his deep pockets," he added.
Other candidates in the race are businessman Jobando Peter (Green Congress Party of Kenya), Mr Ogolla Dickson (Independent), Mr Otieno Samwel (Independent), and Mr Samuel Hodo (PDP).