Cullen was born and grew up in New Hampshire, and moved to Connecticut to attend Yale University.
While a student there, he wrote an op-ed in the New Haven Register criticizing proposals to raise gas taxes, which caught the attention of someone working on John G. Rowland's 1994 gubernatorial campaign.
[1][2] He was later elected chairman of the New Hampshire Republican State Committee, a position he held from 2007 to 2008.
[3] He later served as the executive director of the Yankee Institute for Public Policy for five years, beginning in 2009.
[1][2] He is the author of a book about the New Hampshire primary, entitled Granite Steps,[4] and the founder of the immigration reform advocacy group Americans By Choice.