[4] McMahon's early work for the firm included a role as media strategist for California governor Jerry Brown's 1992 presidential campaign.
[8] Following Dean's departure from the race, McMahon's firm served as the lead advertising partner for the Media Fund, which produced ads in support of then-Senator John Kerry's presidential campaign.
[12][13] During the 2008 election cycle, McMahon produced advertisements for the Democratic National Committee in support of Barack Obama's presidential campaign.
McMahon and Castellanos had often met each other while pitching to clients and decided to form Purple Strategies as a bipartisan consultancy, blending their "blue" and "red" political backgrounds.
[23][24] In addition to his role as a consultant, McMahon is a regular guest commentator on television and has appeared on Today, Good Morning America, Meet the Press, MSNBC's Hardball with Chris Matthews and Andrea Mitchell Reports not to mention frequent appearances on C-SPAN's morning call-in show, Washington Journal.