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Marcus Sebastian Mason

Senior Partner

Marcus Sebastian Mason is Senior Partner at The Madison Group, LLC (TMG) with offices in Los Angeles and Washington, DC.


A native of Los Angeles, Marcus served as both Chief of Staff and Legislative Director for two California Members of Congress. During that time, he initiated and helped to enact several initiatives that impacted the State of California and the nation. Marcus won his first congressional campaign at age twenty-one before beginning his tenure as Capitol Hill’s youngest Chief of Staff. He is a trusted advisor and confident to California elected officials in the City of Los Angeles, County of Los Angeles, and Sacramento as well as California Congressional Delegation and others throughout the U.S.


Marcus served as an advisor to both campaigns of President Barack Obama and as an advisor to the Obama-Biden White House. He also served as a member of the Democratic National Committee and was a Super Delegate. He currently serves as a member of the board of directors of the Congressional Black Caucus Foundation (CBCF)  and the Congressional Black Caucus Political Action Committee (CBCPAC). Most recently, Marcus served as the Chairman of the Biden Campaign’s African American Leadership Finance Council and serves as Senior Advisor to the Campaign’s Co-Chairman and senior leadership team. President Biden appointed Marcus to serve on the Democratic National Committee.


Marcus is the immediate past president of the African American lobbyists association, the Washington Government Relations Group (WGRG). He is a published author who writes spy thrillers under the pen name Sebastian Cheney. He is married to Christina Mary and is the father of three, Taelor Chanel, Romelo and Grace Anne.

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