AND HELL HATH NO FURY...:

High Democratic Turnout Sends a Mixed Signal for November (Kent Garber, February 28, 2008, US News)

[F]or starters, primary turnout rates (in terms of ballots cast) historically tend to be higher for Democrats than Republicans. From 1972 to 2004, there were only two primary elections in which Republicans had a higher cumulative turnout: 1996 (when Bill Clinton, as the incumbent, essentially made Democratic primaries that year irrelevant) and 2000 (when Al Gore, as the sitting vice president, made quick work of Bill Bradley and clinched the nomination early in the campaign). Much of this trend reflects the fact that Democrats, for the past 36 years, have been "out of the White House" more often than in it and therefore have greater incentive to vote in primaries, as well as the rather sizable advantage—17 million more people are registered Democrats than Republicans, as of 2004—they hold in overall voter registration. In fact, even in 1980, when Jimmy Carter, the Democratic incumbent, was on the ballot, the number of votes cast in Democratic primaries exceeded the Republican total by 6 million, or nearly 50 percent.

Second, record turnouts during primaries often fail to yield general election victories in November. Two notable examples would be 1988 and 2000. In 1988, the Democratic Party, bolstered by eight years of a Republican in office, set an all-time primary high of 23 million votes (compared with 14 million in 2000 and 16.2 million in 2004), before losing again to another Republican (George H. W. Bush). The Republicans experienced a similar—if less consequential—problem in 2000. That year, the party had its highest primary turnout in history: More than 17 million votes were cast, breaking the previous record by more than 3 million votes. In November, however, Bush lost the popular vote to Al Gore by more than 500,000 votes.