Figures released by Pennsylvania's Department of State on Monday night showed that Democrats have topped 4 million registered voters, the first time either party in the state has crossed that threshold. Democrats have added 161,000 to their rolls, a gain of about 4 percent; Republican registration has dipped about 1 percent, to 3.2 million.If the long primary campaign is motivating more people to register as Democrats, that's a huge advantage for November. The act of registering causes you to identify with the party you registered with, and once that's happened you're almost certain to vote for that party in the general election too. If Democrats have boosted their rolls by 2-4% nationwide, that's a massive headstart for the presidential election.
That is consistent with the pattern since the beginning of the year: Democratic turnout in primaries and caucuses has topped Republican turnout, often by huge differences.