Governor Jack Ranguma on Friday hit-out at Senator Prof Anyang Nyong'o saying his quest to become Kisumu governor would not benefit residents of Kisumu county.
Mr Ranguma questioned Prof Nyong'o's development record saying he has nothing to show the people of Kisumu to justify why they should entrust him with the county leadership.
Prof Nyong'o has declared interest in vying for the seat of Kisumu governor in 2017.
He is seen as a great challenger to Mr Ranguma because of his close association with Cord leader Raila Odinga.
On Wednesday, he questioned Ranguma's performance saying he had failed to uplift the livelihoods of residents of the county.
From the time Prof Nyong'o declared interest in challenging Ranguma, the relationship of the two leaders has been frosty.
Ranguma has challenged the Senator to prepare for a political duel in 2017 just in case he plunges himself in the gubernatorial contest.
He said Prof Nyong'o should be ready for a rude shock in 2017.
He further said that Nyong'o should be the last person to think about unseating him.