Keen-eyed observers of recent polling data will have noticed that Trump's approval rating has edged up lately achieving the exalted level of 42 percent in 538's rolling approval average. In addition, the generic Congressional ballot has also narrowed so that Democrats now have only a comparatively weak 5 point lead over the GOP in 538's rolling average.
These figures are both the best Trump and the GOP have achieved for almost exactly a year. So...how worried should Democrats be?
Well, here's the thing. Even as this trend has manifested itself, the Democrats' prospects in specific 2018 races have remained very good--if anything, they have improved (see the link to Inside Elections' latest rating changes). And of course, the results of elections that have already been held in 2017-18 have been nothing short of spectacular for the Democrats. Nate Cohn runs it down:
"On average, Democrats have run 14 points ahead of a district’s partisanship (as measured by the last two presidential elections, compared with the national popular vote) in special elections for Republican-held districts so far this cycle. They’ve run more than 20 points ahead on three occasions — Kansas’ Fourth, Pennsylvania’s 18th and Arizona’s Eighth — and that doesn’t include Doug Jones’s victory in the Alabama Senate race.
These Democratic over-performances are a startling departure from the Obama years, when congressional election results polarized along national political lines.
Over the more than 1,000 special and general House elections in Democratic-held districts in the Obama era, there were only four elections when the Republicans ran 20 points ahead of the district’s lean in presidential elections. This cycle’s Democrats have pulled it off three times out of seven.
In a broader historical context, though, the Democratic over-performance is not quite as startling. It is still impressive, but the Democrats ran 20 points ahead of a Republican-held district’s presidential partisanship in 31 races combined in 2006 and 2008.
Over all, the Democrats’ performance in 2018 special congressional elections looks a lot like their showing in open districts in 2006, and well above the average from wave elections in 1994, 2006, 2008 and 2010. On average, Democrats ran 14 points ahead of a district’s partisanship in open races in 2006 — exactly the same as the Democratic over-performance so far this cycle. The Democrats had a similar 10-point over-performance in 2008."
So, there you have it. Some cause for concern, some cause for optimism. Where you land may depend partly on your personality type and partly on your preferred interpretation of the GOP's recent polling uptick. Finally getting payoff from an improving economy? Endless press coverage of Trump scandals actually benefits Trump? Democratic malpractice? Just a blip? Not enough of a swing to counteract Democratic enthusiasm?
Personally, I vote for concerned optimism. YMMV.