" The most volatile factor in our politics in the first decade of the 21st century," Michael Barone writes in the 2010 Almanac of American Politics, "is the balance of enthusiasm." Enthusiastic Republicans turned out in droves to support the GOP and President Bush in 2002 and 2004. By 2006 and 2008, however, Bush's popularity was tanking and the Democrats were bent on "taking the country back" from the right-wing attack/noise/nihilist machine. It's common-sense: The party with the most enthusiastic supporters wins. But it's refreshing to see a truism unfold before your eyes.

Here's the nonpartisan election analyst Amy Walter, for example:

Can Republican Scott Brown really win? If you look at just those who say they are the most interested in voting on Jan. 19, the answer is yes. Among those in the recent Boston Globe poll who said they were "extremely interested" in the race, Coakley and Brown were tied at 47 percent. Last week's Rasmussen poll showed similar results. Among those who said they were most likely to go to the polls, Coakley led by just 2 points -- 47 percent to 45 percent. (Coakley still had an overall lead of 15 points in the Globe poll and 9 points in Rasmussen.) Another less scientific but still telling statistic from the Boston Herald: Brown's crushing Coakley on Facebook. Brown has 20,000 supporters compared to Coakley's 6,000. More interestingly, the "Facebook Women for Brown" group has over 1,000 members, while the "Women for Coakley" group has just 45.

Clearly, there are more than 45 women in Massachusetts who support Martha Coakley (I think). But if those women aren't enthused enough about Coakley's candidacy to join a Facebook group, are they going to canvass neighborhoods and man phonebanks to rally support for their candidate? Doubtful.

"The question for Republican strategists," Barone went on, "is how they can excite potential voters." Over the last year, that question has been answered--and Republican strategists have had nothing to do with it. The way to excite potential Republican voters is for Democrats to govern from the left. Which is exactly what they have done since Obama came to power.