David Wasserman: “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.”
Nate Cohn: “If Democrats keep running ahead of expectations across those plausibly competitive Republican-held seats, many seats will ultimately fall their way. But they will certainly lose more than they win. The question is whether they win enough, and no special election offers the answer to that.”