LoPresti began his political career in 1973 by running in the special election caused by the resignation of Second Suffolk District senator Mario Umana. The then 26-year-old law student upset two state representatives with the support of members of Umana's and Kevin White's organizations as well as Alfred Vellucci and Frederick C. Langone.[4] Following redistricting, LoPresti represented the Suffolk and Middlesex District from 1975 to 1993. During his tenure in the Senate, Lopresti served as chairman of the legislature's Judiciary Committee.[3]
LoPresti died on December 16, 2004, at his home in East Boston.[3]