Before attending law school, Demissie started his political career working on John Kerry's 2004 presidential campaign. He both worked in Iowa and served as its Georgia field director at points in the campaign. During the 2008 United States presidential election Demissie first worked on Hillary Clinton's campaign in the Democratic primaries. Clinton would lose the primaries to Barack Obama. During the general election, he worked as the Ohio get out the vote director for Obama's campaign, holding that position from August 2008 through the November election.