Sonko is expected to appear before the Senate Standing Committee on Devolution and Intergovernmental Relations on Wednesday this week over the composition of the County Executive.
The committee will be seeking an explanation on why Sonko has been operating without a deputy governor for almost one and a half years now.
He will also be required to shed more light on why the county has also been operating without a number of County Executive Committee Members, after previous holders of the positions either resigned or were sent home.
The most recent to resign was Nairobi County Education minister Janet Muthoni-Ouko who quit in January this year.
The Nairobi Governor was expected to appear before the Senate Committee last week but was out of the country.
He was invited before the committee after Nairobi Senator Johnson Sakaja requested for a statement on the proper constitution of the Nairobi County Government.
“…Explain why the County Governor had failed to adhere to the ruling of the Supreme Court which advised that governors should nominate fresh nominees within fourteen days to replace their deputies who resign, die in office or impeached,” reads one of the demands by Sakaja.
The Nairobi Deputy Governor position has been vacant since January 2018 when Polycarp Igathe resigned citing a strained work relationship with Governor Sonko.