Former Meru Governor Peter Munya has joined the National Super Alliance (Nasa) after losing his seat to Kiraitu Murungi of Jubilee.
Mr Munya said he had joined the opposition with the Party of National Unity amid fights over the leadership of the once ruling outfit.
Mr Munya said he had decided to break ranks with Jubilee because his election was stolen.
“I cannot support the same people who stole my votes,” he told reporters at the Capital Hill, the Nasa headquarters.
He vowed to challenge Mr Murungi’s win at the High Court.