Talk to any Republican strategist these days about the November midterm elections and you will get a response very much like this: "It's still early, but I like where we are. A lot." That semi-guarded, we're-not-spiking-the-football-but-we-think-we-will-be-spiking-it-in-November mentality is based on one simple calculation: That midterm elections are almost always a battle between the two parties' bases -- and while the GOP is super-activated heading into the fall, the Democratic base is most decidedly not.

Here's that argument made in a single chart created by Neil Newhouse, a partner with Public Opinion Strategies, a prominent Republican polling firm.

Image courtesy of Neil Newhouse

As the chart shows, four of the major pillars of President Obama's electoral base -- single women, African Americans, Hispanics and young (aged 18-29) voters -- have all experienced a significant decrease in support for Obama over the past 18 months. Before we go further, it's worth noting that the chart compares the percentage of the vote Obama received among these four groups in 2012 with percentages in each group who said they approved or disapproved of how he is handling his job in a March NBC-Wall Street Journal poll. It's not a perfect comparison because, theoretically, people might say they disapprove of how Obama is doing the job and still vote for his party this fall anyway. But, given that we don't have another national election for six-ish months (oh, who are we kidding -- the election is 205 days away), job approval is as good a measure as any to use as a comparative to Obama's 2012 performance.

If Newhouse is right, the above numbers represent a major problem for Democrats this November. Check out this chart -- courtesy of the crack WaPo polling unit -- that compares the 2008 electorate that elected Obama overwhelmingly and the 2010 electorate that handed control of the House back to Republicans.

The 2010 electorate was older, whiter and slightly more male than in the 2008 election. Those are all groups that tend to comprise elements of the Republican base. The key pieces of the Democratic base all played a smaller role in 2010 than they had in 2008. A repeat of that sort of electorate -- which Newhouse believes is the likeliest outcome given the enthusiasm problems within the Democratic base at the moment -- would almost certainly add to Republicans' majority in the House and hand them control of the Senate as well. Democrats are quite clearly aware of the dangers -- it's why Obama talks about the stakes of the election this fall at every fundraiser he does. Of course, talking about getting excited for an election and actually being excited for an election are two different things. And therein lies Democrats' problem heading into November.