The 52 to 48 percent victory by Republican Karen Handel in the Georgia 6th District special election Tuesday is bound to discourage Democrats and encourage Republicans. Ever since Democrat Jon Ossoff won 48.1 percent in the special's first round April 18, he had been regarded as the favorite.

But even with something like $30 million dollars in what became the most expensive House district ever, and with a turnout of 260,000 — more than the 210,000 who voted in the 2014 midterm — Ossoff won exactly 48.1 percent again.

Georgia's 6th was significant because it's a traditionally Republican district whose college-educated voters (59 percent of adults, sixth highest in the country) were repelled by Donald Trump. Mitt Romney carried it 61 to 37 percent; Trump won it only 48.3 to 46.8 percent. That's a huge shift from the persistent partisan patterns that have mostly held for two decades.

The good news for Democrats is that they were able to hold Handel to a Trump-like margin rather than the traditionally expected margin in such a district. The bad news is that there aren't that many other Republican-held super-high-education districts like this one.

Republicans hold only six of the 23 districts with college graduate majorities. Most of these were won years ago by Democrats in elections where the persistent partisan patterns held true. There are only 14 Republican-held districts with more than 40 percent college graduates that were carried by Hillary Clinton, plus four more that Trump carried by less than 5 percent.

These 18 seats are obvious Democratic targets, and the Georgia 6 result suggests that Democrats could be competitive in many of them. But Democrats need a net gain of 24 seats for a House majority. In good years, parties usually gain only half the seats they seriously target.

Moreover, Republican incumbents won 15 of these 18 seats by double-digit margins in 2016, despite the local Trump undertow. Most or all of these incumbents will be running again. And while Democrats may try to field stronger opponents than usual against many of them, Tuesday's result won't help their recruiting efforts.

There's a contrast between Georgia 6 and the three other special elections, which occurred in districts with far lower college-graduate percentages (between 23 and 31 percent) — Kansas 4, Montana at-large and South Carolina 5. Trump carried all three of those by wider margins than Romney did. But in each, Republicans failed to match Trump's showing, and won with results reverting toward or falling below the levels of the persistent partisan pattern.

This is often the pattern in special elections, where you can cast a protest vote without much affecting the balance of partisan power. And it's especially true where, as in these examples, no one expected the incumbent party's candidate to lose. That was especially true on Tuesday in South Carolina's 5, where only 87,000 voted — one-third the turnout in Georgia 6.

In midterm congressional elections, the dynamic is usually different. Incumbents enter with an edge and often without serious opposition. And you can't cast a protest vote without risking a change in party control, a risk that will be palpable in 2018.

And the old maxim that increased turnout helps Democrats might not hold. It didn't in Georgia 6, where high-education Republicans, perhaps unnerved by last week's baseball shooting and constant talk of impeachment, turned out in the driving rain. Higher turnout would probably have helped Republicans in the other three specials, too.

House Democratic Leader Nancy Pelosi presumably realizes this when she cautions fellow Democrats, as she did in 2006, not to frame the election as a referendum on impeachment. Why squander the votes of those who want to check the president but not oust him or hold a pointless Senate trial?

In Politico, Chicago Mayor Rahm Emanuel advises Democrats to do what he did, as House campaign chairman, in 2006. Recruit candidates with local roots and views suited to the local terrain -- and also with sharp political instincts, which both parties' special candidates seemed to lack.

My impression is that none of the Democrats (except maybe Archie Parnell in South Carolina 5) had the political skills and local appeal that enabled so many Democrats to win Republican-leaning seats in the 1970s and hold them in the 1980s. And none of the Republicans showed the political skills and enthusiasm of many Newt Gingrich followers in the 1990s and Tea Partiers in the 2010s.

In 2016, Trump carried 230 House districts and House Republicans won 242 seats. To win a House majority, Democrats need Trumpish results in high-education districts, and improvements in downscale areas on the persistent partisan patterns along which voters with higher and lower levels of education make their choices. It's possible, but it's an uphill climb, and a little more so since Tuesday.