After working as a field organizer for the Michigan Democratic Party in the 2000 presidential election, and then on John Kerry’s campaign for president in 2004, Simon joined Barack Obama's 2008 presidential campaign as the analytics director, based in the Chicago headquarters. As a part of this campaign, he managed stockpiles of data on voter behavior and preferences. His strategy of precision targeting has been credited with helping to identify undecided voters who could be courted by Obama. Following the campaign, he was appointed in 2009 to serve in the Obama Administration at the Department of Health and Human Services, where he focused on healthcare reform and Medicare.