Michael Barone finds some interesting patterns as he crunches numbers for his latest Washington Examiner article:

Only 13 million Americans have voted in Democratic primaries held before Sept. 1, according to Curtis Gans of the Center for the Study of the American Electorate. During the same period, 17 million voted in Republican primaries.

As Gans points out, that’s historic. Democratic primary turnout has been higher than Republican primary turnout in every off-year election since 1930.

That Republican margin may narrow a little as the returns from this week’s primaries come in from states like New York, Massachusetts and Maryland, which have a lot more registered Democrats than registered Republicans. Yet in California, where Democrats have a similar registration edge, almost as many Republicans showed up as Democrats.

What we’re seeing here is a change — a sea change — in the balance of enthusiasm. That’s been critical in a decade in which turnout in presidential years increased from 105 million to 122 million to 131 million. Republicans had a narrow advantage in the balance of enthusiasm in 2002 and 2004. Democrats had a wider advantage in 2006 and 2008. Now Republicans clearly have a wide advantage and have a good chance to sweep the elections six weeks and six days from now.

Barone will help the John Locke Foundation analyze the 2010 elections during a Headliner luncheon panel Sept. 29 in Raleigh.