Erika touched on this earlier but I’m less interested in the four-year trends (enthusiasm overall is down this year compared to 2004 and 2008) than in the monthly trends. The last time Gallup asked voters if they’re more or less enthusiastic to vote than usual was February, when the GOP led 53/45. Fast forward to this month’s poll and the split is … 51/39, with both parties’ numbers having dipped but the Dems’ down more sharply. How come? Is it a seasonal thing in election years? Maybe, maybe not:

Enthusiasm built steadily throughout the campaign in 2004 but it fell off a cliff in 2008 during the summer months before rebounding in the fall. The difference in those two years, I assume, is the epic Democratic primary between Obama and Hillary. Kerry had a relatively easy time of things in the primary so Democratic voters could focus on the general election from the outset. Not so in the death struggle of ’08; what you’re seeing in those numbers, in all likelihood, is a massive letdown among Hillary fans over the summer after she lost, with the predictable rebound in the fall as Democrats “came home.” Santorum tested Romney briefly in February and March but this year’s GOP primary was a lot more like the Democratic one in 2004 than in 2008 — and yet enthusiasm is still down a few points over the summer. In fact, although it’s Democrats who have slipped most since February, it’s actually Republicans who have slipped most since September 2011. Back then, Dems split 45/44 on the question of more/less enthusiasm while the GOP split 58/30. We’ve lost seven points over the last 10 months while Democrats have lost six. Why is that? Is it an artifact of the somewhat-contested primary or conservative tepidness towards Romney?

More from Gallup on the GOP’s overall advantage:

The voting enthusiasm measure gives a sense of Americans’ motivation to turn out and vote but probably also their expectations of their preferred party’s chances of winning. Thus, the Republican advantage may indicate a greater likelihood of voting among Republicans but also greater optimism about a Republican victory than was the case in 2008. In turn, Democrats are probably less optimistic about their chances of winning than they were in 2008.

Gallup has found a relationship between voting enthusiasm and the outcome of midterm congressional elections, with the party that has the advantage generally faring better in the elections. That pattern also held in the 2008 presidential election, with Democrats reporting greater enthusiasm throughout the year and Barack Obama winning the election.

All well and good, but don’t read too much into the GOP’s advantage here. Democrats led Republicans by 17 points in enthusiasm at this point in 2004 and we all know how the incumbent fared that time. But never mind that. Again, I’m wondering: Why has Democratic enthusiasm slid more over the past five months than the GOP’s? The most striking thing about Obama’s campaign strategy this year is how he’s scaled back his outreach to white working-class voters and other groups outside his base to focus on pandering to true-blue Dems in hopes of boosting turnout. That’s what his gay marriage “evolution” and his DREAM Act gambit were all about. And yet, if Gallup is to be believed, he’s eating a big ol’ shinola burger for it in terms of liberal enthusiasm. That doesn’t mean much yet — note how the 2008 numbers enthusiasm soared in September — but it’s still hard for me to explain. Are liberals just bored with the election? (Aren’t we all?) Depressed about the forever elusive economic recovery? (Surely.) Sick of The One’s face on TV every five minutes? (Possibly.) Okay, but still — the man’s delivering Grade A prime class resentment day after day with those Bain attack ads to try to get them excited. What more do they want?

Here’s Krauthammer insisting that, contrary to popular belief, he does in fact think Romney will win in November.