Ashton Carter, the longtime Pentagon insider whose nomination as defense secretary was announced Friday by President Obama, is a man of impeccable educational credentials: undergrad at Yale, followed by a Rhodes scholarship and a doctorate in theoretical physics from Oxford.

If Carter’s pedigree sounds familiar, it should: Obama’s Cabinet is currently loaded up with graduates of elite institutions.  As shown in the table below, no less than two-thirds of Obama’s Cabinet appointees attended an Ivy League institution—and an astounding 13 out of 21 of these officials went to either Harvard or Yale.

Compare the list of degrees held by Obama appointees — and even most of the non-Ivies would warm the heart of any high-school guidance counselor — with the educational credentials of the officials in George W. Bush’s Cabinet.  (The table displays appointees holding posts when the Bush administration ended in 2009.)  Only six out of Bush’s 20 Cabinet-level officials held Ivy League degrees, and many of his appointees attended schools not well known outside of their regions.

The stark contrast between the exalted educational backgrounds of Obama’s Cabinet and the more salt-of-the-earth schools attended by Bush officials may come as a surprise.  After all, the Democrats are the party that — even in 2014 — won a majority among voters making less than $50,000 per year.

But upon a closer examination of the two parties’ coalitions, the elite origins of the Obama administration’s top appointees make more sense.  Democratic Party identification is strong among the nation’s most-educated voters.  In fact, surveys in recent elections have identified a non-linear relationship between educational attainment and support for the Democrats: the party performs best among those with a post-graduate education and among those without a high-school diploma.  This pattern was long in the making: as sociologists Clem Brooks and Jeff Manza show in their book “Social Cleavages and Political Change,” those in the professional classes have become increasingly Democratic since the 1970s.

A result of this shift is that Democratic voters now value elite educational credentials slightly more than Republicans.  In April, the Pew Research Center asked Americans about the kinds of experience and traits they like in presidential candidates.  Not surprisingly, big differences emerged between partisans on traits such as being a woman or having “Washington experience” (valued more by Democrats) or being a business executive or an evangelical Christian (favored more by Republicans).  The survey included another characteristic that is remarkably relevant to the topic at hand.  It asked Americans whether they’d be more likely to support a candidate who “attended a prestigious university such as Harvard or Yale.”  Among Democrats, 24 percent said this would make them more likely to support a candidate; among Republicans, only 15 percent did.

There are,  of course, many other reasons why Democrats might look to alumni of elite institutions to staff key positions more than Republicans—not least of which is that the G.O.P. is more likely to draw its appointees from the ranks of private industry.  But the persistent differences in educational attainment between the two parties’ coalitions—and the higher premium placed on educational credentials among Democrats—suggest that many Ivy League graduates and their elite compatriots will continue to be seated around the table in the Cabinet Room whenever a Democrat is in the White House.