Democrat Dan McCready and Republican Dan Bishop
CNN  — 

The seemingly never-ending election to represent North Carolina’s 9th Congressional District will (probably) come to a close on Tuesday.

For those who don’t recall, credible allegations of ballot fraud caused the State Board of Elections to order a new election in the district after the final tally found Republican Mark Harris ahead of Democrat Dan McCready by fewer than 1,000 votes.

Harris decided not to run again in the special election. Instead, McCready will face off against Republican Dan Bishop. The race looks like it could be close, which could foreshadow bad news for the Republicans in 2020.

There hasn’t been any non-partisan live interview polling of the district, but data that has been released to the public shows a close race. No poll released to the public has had either up by more than 4 points.

When you look back at polling miscues in special House elections, even an error of 13 points falls within the 95% error band. In other words, anything from a Bishop win by 13 points to a McCready win by 13 points shouldn’t surprise us.

Republicans should be dominating this district. President Donald Trump won it by 12 points in 2016. Mitt Romney won it by 12 points in 2012. To give you some perspective of how unusual it would be for a Democrat to win such a Republican district, keep in mind that Democrats represent only four districts won by a larger margin.

While some of the 9th district is in the suburbs of Charlotte, it’s not like other suburban districts where Democrats have gained a lot of ground in the Trump era. About 34% of adults 25 years and older have a college degree in the district, which is about equal to the 32% who have one nationwide. The districts where Democrats have been doing better during the Trump administration (like those in Texas) tend to be much better educated than the nation as a whole.

One advantage McCready may have is that Democrats maintain an 8-point voter registration advantage in the district. As I noted before last year’s special election in Pennsylvania’s 18th district, feelings towards a president and partisan difference in voter registration seem to play a role in determining a person’s House vote. Therefore, Republicans’ strong presidential performances in North Carolina’s 9 may undersell the chance McCready has, given the district has more registered Democrats than Republicans.

If McCready comes close to winning, this special election will be another one in which Democrats outperformed how Hillary Clinton did in 2016. You may recall Democrats did over 10 points better than Clinton in the average special congressional election in 2017 and 2018. This presaged them easily taking back the House in the 2018 midterms.

And let there be little doubt: Trump’s name may not be on the ballot, but a lot of this election is about him. Bishop is using Trump heavily in his advertisements, and the President is holding a rally in the district on Monday night.

I would, however, be cautious about reading too much into any one special election. If Democrats do better than their 2016 baseline in many special elections, that is far more concerning for Republicans than if they outperform it in one. In the only other special congressional election this year, the result looked very similar to the 2016 presidential outcome.

Further, a look at history suggests that special elections may be less useful for forecasting presidential elections than midterm elections. Republicans romped in the 2015 and 2016 special House elections, while the 2016 presidential election was quite close.

Still, in this era in which feelings toward a president seem to be more determinative of vote choice than at any point in recent history, a Democratic victory or a close GOP win in a district Trump won by 12 in 2016 would be suggestive that Trump’s brand is tarnished ahead of 2020.