(CNN) CNN has projected that Republicans won the special election in Arizona's 8th Congressional District, but once again Democrats have overperformed in a deep red district, in another sign the national environment is in the their favor.

The vote count is not final, but Republican Debbie Lesko is currently ahead of Democrat Hiral Tipirneni by about a 5-point margin.

In a neutral environment, the margin should be much wider. President Donald Trump won the district by 21 percentage points in 2016 and Mitt Romney won it by 25 percentage points in 2012. Combining those outcomes and controlling for how well Democrats did nationally in each of those contests, we can say that Arizona 8 is 25 points more Republican than the nation. Lesko looks like she's going to do about 20 percentage points worse than that.

The result in Arizona 8 fits a pattern so far in special congressional elections this cycle. In every one of the nine so far, Democrats have outperformed the partisan baseline based on the prior two presidential elections.

Including Arizona 8, the average improvement for the Democrats has been 17 percentage points versus the partisan baseline. That's better than any party out of power has done in the lead-up to a midterm cycle since at least 1994.

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