The following experts were interviewed for this article

Norman Ornstein, resident scholar, American Enterprise Institute
James Russell Muirhead, Jr., professor of political science, Dartmouth College
James Thurber, professor of government, American University
Sean Theriault, professor of government, University of Texas at Austin
Thomas Mann, senior fellow, Brookings Institution
Robert C. Smith, professor of political science, San Francisco State University
Laurel Harbridge, professor of political science, Northwestern University
David Greenberg, professor of history, Rutgers University
Hans Noel, associate professor of government, Georgetown University
William Howell, professor of political science, University of Chicago
Morris Fiorina, professor of political science, Stanford University
Brian J Gaines, professor of political science, University of Illinois
Robert Shapiro, professor of government, Columbia University
Dianne Pinderhughes, professor of political science, University of Notre Dame
Stephen Ansolabehere, professor of government, Harvard University
Alexander Bateman, assistant professor of government, Cornell University
Elizabeth Sanders, professor of government, Cornell University
Wendy Schiller, professor of political science and international & public affairs, Brown University
Matthew Levendusky, associate professor of political science, University of Pennsylvania
Michael Munger, professor of political science, Duke University
Jack Rakove, professor of history, Stanford University
Bruce Miroff, professor of political science, State University of New York Albany
Timothy Patrick McCarthy, adjunct lecturer on public policy, Harvard Kennedy School