Mr. Halpin, a lifelong Long Islander, began his public service at 26 as a Suffolk County Legislator (1979–82) and later became the first Democrat in over a century to represent his Assembly district (1982–87), where he chaired the Ethics Committee and the Subcommittee on Long Island Marine Resources.

In 1987, at 34, he was elected Suffolk County Executive — the youngest in county history — serving from 1988 to 1991. His administration expanded housing for families and veterans, launched community policing and anti-domestic violence programs, introduced DARE in schools, and advanced a nationally recognized open space preservation initiative.

Mr. Halpin joined the Suffolk County Water Authority in 2006, becoming Chair in 2018, where he safeguarded clean drinking water for over one million residents while improving efficiency, transparency, and public health protections.

Beyond government, he served as Executive Vice President of the Institute for Student Achievement and later as Managing Director at Mercury Public Affairs LLC until 2023. He has announced his candidacy for New York’s 2nd Congressional District, covering the south shore of Nassau and Suffolk Counties.