Between the 2004 and 2008 presidential elections, the Democratic Party substantially widened its margin in party identification: 38% of voters identify themselves as Democrats compared with 28% Republican and 34% independent. These data are based on more than 28,000 interviews conducted by the Pew Research Center in 2008 prior to the November election. In 2004, party affiliation was far more closely divided: 35% Democratic, 33% Republican and 32% independent. Notably, many gains in party affiliation have come in swing states. In Virginia, Democrat hold a five-point advantage over the GOP (34% to 29%), while voters were split in 2004, and in Ohio a two-point GOP advantage has become a nine-point Democratic lead (37% to 28%). Read More

Russell Heimlich  is a former web developer at Pew Research Center.