The 40th district includes parts of Rockland, Putnam and Westchester counties in the Hudson Valley.

[2] In 2015 he left the legislature to work in the administration of New York Governor Andrew Cuomo as assistant director of the Office of Community Renewal.

[5][10] In 2018, Harckham was recruited to run against incumbent Republican state Senator Terrence Murphy.

[11] While the district was competitive, Murphy was believed to be a formidable candidate who was less vulnerable than some of his GOP colleagues.

[15][16] Harckham was reelected to the Senate in 2020 in a race against former Westchester County Executive Rob Astorino.

[18] Harckham serves on the Committee on Alcoholism and Substance Abuse and the Joint Senate Task Force on Opioids, Addiction & Overdose Prevention.