[3] As an undergraduate student at Wesleyan University in Middletown, Connecticut, Lesser was elected president of the College Democrats chapter and ran voter registration drives.
[5] In May 2008, Lesser, then a student at Wesleyan University, was selected to run as the second youngest candidate for State Representative at the Democratic 100th District Convention.
[8] Lesser also received support from State Senator Tom Gaffey and Middletown DTC Chairman Dan Russo.
[17] In 2013, Lesser voted in favor of the gun control bill that passed in the wake of the Sandy Hook Elementary School massacre.
[20] In May 2018, Lesser announced a run for state senator from the 9th district,[21] which includes Cromwell, Newington, Rocky Hill, and portions of Middletown and Wethersfield.
[23] The general election featured some controversy when the campaign of Republican nominee, Ed Charamut, of Rocky Hill, sent out a mailer to voters attacking Lesser, featuring an altered image of Lesser clutching $100 bills; the mailer garnered national media attention and was denounced for its use of antisemitic tropes.
[24][25][26] Lesser won the general election in November,[26] and was appointed Senate chairman of the Insurance and Real Estate Committee the following month.
[29] As a state senator, Lesser has written laws to guarantee mental health parity,[30] expand access to epinephrine devices (such as EpiPens) in public venues,[31] and to cap the cost of insulin at $25.
[46] After Governor Ned Lamont's staff agreed to "mediate" issues raised by Lesser, he ended questioning and voted against the bill.
[50] He was appointed executive director of the Cancer Support Community of Southern Connecticut (which serves New London, Middlesex, New Haven and Fairfield counties) in 2014.