He proceeded to Kisii High School for his A- level Secondary Education where he completed in 1977.
Rasanga joined the University of Nairobi in 1979 and graduated with a Bachelor of Arts in Economics degree in 1981.
To advance his knowledge in procurement, he joined the Kenya Institute of Administration (KIA) where he attained a Diploma in Supplies Management in 1985.
The Orange Democratic Movement selected Rasanga as its candidate after a disputed nomination between Oburu Odinga and Oduol.
Rasanga clinched the governorship in a subsequent by-election and became the first governor-elect of Siaya County.In 2017 he won the gubernatorial seat again flooring the then public accounts committee chair and Rarieda Mp Nicholas Odero Gumbo[3]