After serving briefly as an advisor on Senator John Kerry's 2004 presidential campaign, Lu began working for Barack Obama in 2005 in his U.S. Senate office, where Lu served as legislative director and acting chief of staff. Following Obama's successful 2008 campaign for presidency, Lu was appointed executive director of the Obama-Biden Transition Project. When Obama appointed Lu as Cabinet Secretary, "The New York Times" described him as "one of the highest-ranking Asian Americans in the Obama administration".