A few weeks ago, NBC/National Journal's Matthew Berger reported that there were 101,499 new Democratic applications and 132,688 others who switched to the Democratic Party in Pennsylvania since January 1, compared to just 32,191 new Republican registrants and 13,937 switchers. Overall, these increases boosted the Democrats to a 900,000-voter registration advantage (4.1 million v. 3.2 million), an almost 50 percent increase over the 630,000-plus advantage Democrats enjoyed as recently as November 2007, according to the Pennsylvania secretary of state's office.
So that bodes well for the Democrats in November, a point Holly Yeager makes quite convincing and eloquently in her online piece for the Prospect. But what, if anything, do the registration trends tell us about what’s going to happen tonight in the Democratic primary race between Hillary Clinton and Barack Obama?
Nobody can be sure, and without seeing the county-by-county numbers the following is entirely speculative. But, as a general rule, I think it's fair to say that the conventional wisdom is that a rise in new registrants should tend to favor Obama. Pennsylvania has a closed primary and so Clinton is depending upon support from core Democrats. New registrants are by definition new converts rather than longstanding Democrats. Furthermore, whatever the trends in the polls (which have narrowed during the past six weeks) new registrants are likely to be missed or screened out by likely-voter polling samples.
Clinton is favored to win today and I think she probably will. But if she doesn't the reason is that, for the first time since January, the candidates had significant time to campaign as if this were the general election and change the composition of the electorate by registering new voters. Obama and his advisers argue incessantly that when and where he has the resources to engage in an all-out campaign to register and mobilize voters, they do well. Today will be a great test of that premise.
--Tom Schaller