LONDON: Rob Blackie, Blue State Digital's EMEA MD, is understood to have resigned from the firm earlier this month.
The agency has worked with the Labour Party in the UK since March.
Sources at the firm confirmed Blackie's departure but declined to comment further.
It is understood that Blackie's responsibilities have been taken over by Sam Jeffers, a director in the agency's London office.
Industry sources have suggested that Blackie's departure was due to discord with Blue State Digital's US headquarters. The agency declined to comment on the suggestion.
The firm recruited Blackie from Blue Rubicon in 2011, putting him in charge of its UK-based operations and its European expansion plans.
Blue State Digital's managing partner and CEO in the US, Thomas Gensemer, left the firm to become US chief strategy officer at Burson-Marsteller in July. He is based in Burson's New York office, focusing on developing integrated campaigns, product offerings, and thought-leadership strategies.
Blue State Digital was cofounded by Joe Rospars and Jascha Franklin-Hodge in the US and is known for its pioneering digital work on President Obama's first presidential campaign in 2008.
The agency was acquired by WPP Group at the beginning of 2011.
Blackie could not be reached for comment at the time of publication.
This story originally appeared on the website of PRWeek UK.