Amani National Congress party leader Musalia Mudavadi now says ODM leader Raila Odinga should prepare to exit from active politics.
The two leaders have been at loggerheads, with their political rivalry escalating over the Kibra by-election scheduled for tomorrow (Thursday).
On Tuesday, Mudavadi insisted that Odinga's time in politics is up, adding that he should be ready for permanent retirement.
"His time is up. The whole country knows that Raila has ridden on the backs of others in 2013, and 2017. He is trying to do the same in Kibra," Mudavadi said through Barack Muluka.
ANC backed Raila's candidature in 2017 but the party has since pulled out, accusing Mr Odinga of insincerity. Part of the controversy is fueled by Sh4 billion which ODM is reluctant to share.
"ODM seems to be suffering from the Nile factor. Their public pronouncements are increasing juvenile. When they are not juvenile they are senile or both," added the Mudavadi.
But Raila, through ODM Secretary General Edwin Sifuna, said Mudavadi was behaving like a jilted lover.
"This outburst must be seen in the context of a jilted lover, a parasite abandoned by its long-suffering host. Musalia is easily the biggest baggage our party leader has had to carry since 2002. Now that Raila has taken away that support, Musalia needs to be a man," Raila said in a statement signed by Sifuna.
In 2013, Mudavadi finished third behind President Uhuru Kenyatta and Raila Odinga. Mudavadi was appointed by Raila as Deputy Prime Minister in 2008.
During the 2017 polls, Mudavadi was the chief agent of National Super Alliance (NASA) whose flag bearer was Mr Odinga. He disputed the outcome.
Ever since Odinga resolved to work with President Uhuru Kenyatta, Mudavadi has been accusing him of dishonesty. They are yet to share a platform.