After graduating from college, Miller worked as a press secretary for Congresswoman Michele Bachmann and Congressman John Shadegg, both members of the Republican Party.[33] Miller started working for Alabama Senator and future Attorney General Jeff Sessions in 2009,[33] rising to the position of communications director.[20] In the 113th Congress, Miller played a major role in defeating the bi-partisan Gang of Eight's proposed immigration reform bill.[20][33] As part of his role as communications director, Miller was responsible for writing many of the speeches Sessions gave about the bill.[34] Miller and Sessions developed what Miller describes as "nation-state populism," a response to globalization and immigration that would strongly influence Donald Trump's 2016 campaign. Miller also worked on Dave Brat's successful 2014 House campaign, which unseated Republican Majority Leader Eric Cantor.[20]