O'Leary represented the 5th Suffolk District in the Massachusetts House of Representatives from 1965 to 1969.[1] He then went on to serve on the Boston City Council from 1968 to 1975. He was the Council's President in 1969 and from 1974 to 1975. He ran for the United States Senate in 1972, but lost to Middlesex County District Attorney John J. Droney in the Democratic primary. In 1979, he was elected to the Boston School Committee. He resigned on October 4, 1980, after being arrested and charged with attempting to extort a $650,000 kickback from a school bus company.[3] He pleaded guilty to violating the Hobbs Act and was sentenced to eighteen months in prison.[4]
O'Leary had a wife, who died of breast cancer, and 5 daughters who remain alive today. He has 3 grandchildren.