Since Belknap and Campbell tied the concept of party identification to political behavior in 1951 (Belknap and Campbell 1951), party affiliation has played a central role in explanations of individual political behavior in the United States. Indeed, as Nie, Verba, and Petrocik noted in 1979 (p. 47), in the 1950s and 1960s, party identification "was the central thread running through interpretations of American politics" where it was considered "a stable characteristic of the individual: it was likely to be inherited, it was likely to remain steady throughout the citizen's political life, and it was likely to grow in strength during that lifetime."
The drop in the number of citizens reporting a strong tie to party, a drop that occurred between the mid-1960s and mid-1970s and leveled off in the late-1970s and early-1980s, did not change the fact that most continued to identify with a party. But the change in partisan affiliation did focus scholars on its change from one election to another. Abramson, Aldrich, and Rohde spotted the phenomenon on which we focus here in 1994, when they observed that "over the past forty years, the balance between the two parties has favored Democrats by a range of about 55/45 to about 60/40. While the results from the last four presidential election years still fall within that range, they show a clear shift toward the Republicans" (p. 224).
Both the 2004 National Annenberg Election Survey (NAES) and surveys by the Pew Research Center for the People and the Press show that the gap in self-identified party affiliation between Democrats and Republicans is closing. However, because Republicans continue to have higher turnout than Democrats, this difference did not produce a net Democratic advantage on Election Day 2004 when, for the first time since modern exit polling began in 1976, the number of self-identified Republicans who voted equaled the number of people saying they were Democrats (37 percent each; National Election Poll, Pew Research Center for the People and the Press 2005). As Kerry-Edwards's pollster Mark Mellman observed at the 2004 Annenberg Election Debriefing, "In the 70s and 80s, Democrats on Election Day had 15-point margins. By the time we got to the 80s, those were 2 and 3 and 4-point margins. It is right to say that today this was the first election where the exit polls showed parity" (Jamieson 2003). In 2000, the NAES and the U.S. National Election Study (NES) observed a narrowing of the gap (Johnston, Hagen, and Jamieson 2004, 42-43). While this narrowing was picked up in pre-election polls, it had not yet occurred in Election Day exit polls.
Research Questions and Methodology
This Election Day parity invites the questions that we address in this article. How stable was party affiliation during the course of the entire 2004 presidential campaign? Was Republican self-identification consistently rising as the campaign progressed, or was there a noticeable level of variability across the campaign? Also, how does 2004 party identification compare with 2000? Were any changes across 2004 simply the continuation of a pattern evident four years earlier? If there is a narrowing gap between Republicans and Democrats, how does that change the demographic and geographic makeup of the parties? Finally, what impact, if any, has the shift had on the number of registered voters who call themselves Independents?
Our analysis goes beyond the extant research which has a focus on party changes from campaign to campaign over time. Instead, the NAES examines changes that occur within the course of an election year.
Using a rolling cross-sectional design (Romer et al. 2004) created for it by Richard Johnston who had pioneered its use in Canadian elections, the 2004 NAES interviewed 81,422 adults by telephone from October 7, 2003 through November 16, 2004; 67,777 registered voters were part of the 2004 sample. The 2000 NAES was conducted by telephone from December 14, 1999 through January 19, 2001 among 58,373 adults, of which 46,697 were registered voters (for an analysis of 2000 NAES data see Johnston, Hagen, and Jamieson 2004). …