Zellner first joined the
Erie County Democratic Party in 2003 working as a volunteer. In
2016, Zellner served on the
Hillary for America National Finance Committee, and was a statewide delegate at the
2016 Democratic National Convention. and previously served as chair of the legislative committee of the New York State Elections Commissioners Association. Zellner was declared the winner an hour after in-person voting ended, beating Dan R. Gagliardo, who ran on the
Republican and
Conservative ballot lines. He serves as Chair of the Procurement and Contracts Committee, and is a member of seven other standing committees. ==Personal life==