Score one win for Donald Trump early in the 2020 election cycle. After getting Trump’s endorsement and a significant amount of campaign support, Fred Keller easily defeated Democratic opponent Marc Friedenberg in a special election to fill the House seat in Pennsylvania’s 12th congressional district.

Is this a harbinger for next year, or simply a district returning to its normal partisan position?

Republican state Rep. Fred Keller easily defeated Democrat Marc Friedenberg in a special election Tuesday in Pennsylvania’s 12th District. With 98 percent of precincts reporting, Keller led the Penn State professor, 67.8 percent to 32.2 percent.

The result was not unexpected given that President Donald Trump would have carried the deep-red seat by 36 points in 2016 under the current congressional lines.

Trump traveled to the district Monday to boost the state lawmaker. He also recorded a robocall encouraging voters to support Keller and praised him in a tweet Tuesday.

Trump supporters hailed this as an indication that momentum is swinging back after the disappointing midterm elections six months ago. It’s always tricky to use special elections as harbingers, however, especially with seventeen months to go before Trump runs for re-election. As Roll Call notes, PA-12 might have just reverted to form as a strong GOP district. It has a Cook index of R+17, which still shows that Keller overperformed, but a wide win was predictable. It helped that the seat became vacant when popular Republican incumbent Tom Marino resigned over health issues rather than scandal, although he had to withdraw from an appointment to the Trump administration over criticism of legislation he sponsored.

However, CNN’s Harry Enten argues that this may well be a harbinger — and it’s not the only one:

Over the nearly two-year period prior to the 2018 midterms, congressional Democratic candidates were regularly outperforming the 2016 presidential baseline. The average Democratic margin across 11 congressional elections was 12 points better than Clinton’s margin in the same district (or state, in the case of the 2017 special Senate election in Alabama). This included outperforming Clinton in nine of these 11 races.

The question is whether the Pennsylvania 12 result is a fluke. It could be, but about 30 special legislative elections since the 2018 midterms suggest that something may very well have changed since last year.

According to data collected by Daily Kos Elections, Democrats have only been outperforming Clinton’s margin by about 3 points heading into Tuesday night in these state legislative specials. Even if we allocate third party votes proportionally to account for a number of races with strong third-party showings, Democrats have only been outperforming the 2016 baseline by about 6 points.

Either of these measures lags the average 10 point overperformance Democrats had from after Trump’s election to just before the 2018 midterms.

This might well be why Nancy Pelosi keeps fighting to hold the line on impeachment talk. Democrats’ wide-ranging push to paralyze the Trump administration through investigations might have shifted voter enthusiasm in 2020, even more than Trump himself at the top of the ticket does. In the meantime, as NBC’s Chuck Todd points out and I noted earlier, Democrats have tied themselves into knots over impeachment and have nothing else to show for themselves:

As House Speaker Nancy Pelosi tries to prevent her Democratic colleagues from rushing to impeachment proceedings, it’s worth asking again:

Five months into their majority, what do House Democrats have to show for it? …

And what’s the plan for 2019? Is it triumphing over Trump in the courts? Is it finding damaging information that could hurt Trump next year – a la how House Republicans Benghazi-ed Hillary Clinton in 2015?

Because one reason why House Democrats are growing restless – and increasingly talking about impeachment — is that they have little to show for their majority.

Pelosi knows, though, that an impeachment would paralyze Congress for the entire session as much as it would paralyze the Trump administration, maybe more. If Democrats had a prayer of removing Trump, it might be worth it, although all it would do is set up Mike Pence to run the revenge campaign in 2020. However, they won’t get 20 Republicans to cross over to remove Trump; they likely wouldn’t get enough for even a simple majority. It would waste two years of Democrats’ control of the House; worse yet, it would enrage Republican voters while failure would disillusion Democratic voters. Even the impeachment-lite talk from Pelosi could backfire in this manner, once it becomes clear that impeachment won’t actually happen.

That may already be happening, and might account for the shift Enten sees in PA-12 and elsewhere. If so, Pelosi and her caucus spent today making things worse, albeit more incrementally than they might otherwise have.