Makueni Governor Kivutha Kibwana has ditched Muungano party to join Kalonzo Musyoka's Wiper party.
Kibwana and Kalonzo signed a working formula for the Governor to vie again for Makueni's top seat on a Wiper ticket.
"We will table the documents to the National Governing Council in Wiper for ratification. That is where issues of direct nomination will be discussed," Kalonzo said on Thursday.
The Wiper boss said the pact resolved persistent differences between Kibwana and Makueni Senator Mutula Kilonzo Jr.
"From today Mutula and Kibwana will be speaking in one voice," he said, adding they will be crucial pillars in the National Super Alliance.
Muungano supporters said they had no problem with Kibwana working with Kalonzo provided he is nominated directly.
Kibwana said the party will not dissolve as it intends to field candidates in all elective posts except the presidency.
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But he pledged his full support for Kalonzo, saying he was a peaceful leader who would never bow to corruption.
"If I helped former president Mwai Kibaki in his administration, then I promise to do the same to you and help you in your presidential bid," said Kibwana.
The Governor has been under immense pressure from Kalonzo and other leaders to ditch Muungano and join Wiper to strengthen and give it negotiating power in Nasa.
The pact was signed at Ngwata technical institute in Kibwezi East.
Among those present were Makueni Deputy Governor Adelina Mwau, Machakos woman representative Rose Musyoka and MPs Jessica Mbalu (Kibwezi East) and Daniel Maanzo (Makueni).