Republicans won a high-profile special House election in Georgia, as well as a lower-profile race in South Carolina. The latter was surprisingly close. David Wasserman writes:
The divergent results in GA-06 and SC-05 prove saturation-level campaigns can backfire on the party with a baseline enthusiasm advantage—in this case, Democrats. The GA-06 election drew over 259,000 voters—an all-time turnout record for a stand-alone special election and an amazing 49,000 more than participated in the 2014 midterm in GA-06. The crush of attention motivated GOP voters who might have otherwise stayed home, helping Handel to victory.
Credit must be given to the NRCC and the House GOP leadership-allied Congressional Leadership Fund, who did more with less and ran straightforward, but effective ads to buttress Handel's imperfect campaign and neutralize Ossoff's enormous advantage on the airwaves. Trump's approval rating in GA-06 was still mired in the low 40s by this week, but the GOP was still able to compound and capitalize on serious Ossoff fatigue.
By contrast, SC-05 drew fewer than 88,000 voters despite its similar population. Norman, the Republican nominee, had just emerged from a tight runoff with critical backing from the Club for Growth, but had alienated some of the district's chamber of commerce types. Meanwhile, Parnell benefited from a base of highly motivated Democrats, including a modest and low-profile DCCC effort to turn out African-American voters.
Although it's true Democrats have agonizingly yet to capture a red district, they have outperformed their "generic" share of the vote significantly in every contest. Measured against the Cook Political Report's Partisan Voter Index (PVI), Democrats have outperformed the partisan lean of their districts by an average of eight points in the past five elections...
If Democrats were to outperform their "generic" share by eight points across the board in November 2018, they would pick up 80 seats. Of course, that won't happen because Republican incumbents will be tougher to dislodge than special election nominees. But these results fit a pattern that should still worry GOP incumbents everywhere, regardless of Trump's national approval rating and the outcome of the healthcare debate in Congress.