Ex-Machakos senator Johnstone Muthama believes the decision by James Orengo to take over as Senate Minority Leader would taint his reputation as a democrat.
Last month, Orengo triggered a crisis within NASA, which has been attributed to persistent crisis in the opposition coalition.
While appearing on Citizen TV on Tuesday, Muthama however defended the actions by Wiper party to re-brand to One Kenya Movement.
"Personally, I never expected him to accept the appointment. It was against the spirit of NASA.
"His decision to accept it would ruin has admirable record as a champion of democracy," said Muthama.
The Siaya senator took over from Moses Wetangula, albeit controversially despite calls to decline the appointment.
At a rally in Siaya recently, Orengo however defended his decision, terming it a 'minor structural' change within a democratic coalition.