In a normal year, a special congressional election in Pennsylvania’s 18th District (a highly red area that includes the southern suburbs of Pittsburgh and surrounding rural areas) wouldn’t be a huge deal. Trump carried the district by about 20 points in 2016, so Republicans should have been able to win the district, easily. Yet as of this morning, the race in this ruby-red district is still too close to call. And that’s a very bad sign for the GOP.

To see why, first take a look at this graphic—it shows the results of every special election in the Trump Era compared to 2016.

Here’s how the graphic works: Each point represents a special election, and the size of the point is proportional to the number of votes cast for major party candidates. The vertical position of each point represents how the margin compared to Trump’s 2016 margin (points above the dotted line represent Democratic over-performances and points below it are Republican over-performances). The graph reads left to right chronologically. And the color represents the result—pink means Republicans held the seat, dark blue indicates a Democrats flipped it, dark red means Republican flip and light blue means Democratic hold.

The large point at the far right hand side of the graphic is PA-18. It’s far above the dotted line (zero), indicating a huge Democratic overperformance. It’s also one of the larger points on the graphic—meaning that more people voted on Tuesday than in the vast majority of special elections in the last 14 months.

In most special elections during the Trump era, Republicans have underperformed the Trump’s 2016 margin. Saccone is no exception—the election was essentially tied in a district that Trump won in a blowout. That’s worse than the average Republican underperformance (Daily Kos Elections had Republicans on average underperforming Trump’s margin by 13 points as of Tuesday night), which is bad. But when you put it in context, it’s actually not that far off some other races we’ve seen during the Trump Era. (Remember Kansas’s 4th District, where the Republican won a special election by seven points after Trump won it by 27 points in 2016.)

Trump partisans might want to write off these results as a fluke (Saccone was a bad candidate; special elections have weird turnout; Democrats have poured a lot of money into these races). But the numbers are a part of a broader pattern. President Trump is historically unpopular, and his bad poll numbers are hurting Republicans up and down the ballot. In recent elections, rank and file Republicans have failed to turn out and, in some cases, moved towards the Democratic party. In generic ballot polls ( one of the best predictors we have of the eventual midterm result), Democrats lead Republicans by a solid margin. And Republican members of Congress have been retiring at a breakneck pace.

Every single indicator suggests that agree that Trump’s unpopularity has hurt Republican candidates—including Saccone—and will continue to do so through November.

And while the outcome of this race likely won’t influence policy much (the winner will represent a disappearing district for a few months in a GOP-dominated chamber), it may influence the dynamics of the midterms quite a bit: Because Republican House members contemplating reelection this year and high quality Democratic challengers who are on the fence about running are paying a lot of attention to it.

According to Daniel Donner’s tracker, 36 Republicans have already decided to retire this year rather than run for reelection. That pace is a fast compared to previous years. Last night’s results, put in context with that chart, are going to hammer home to the rest of Republican incumbents that 2018 isn’t just likely to be a good year for Democrats—it may be a year where members from a normally solidly Republican district are vulnerable. It’s not hard to imagine more of them deciding to hang it up rather than risk defeat after watching last night’s results.

And Democrats will use this race as a recruiting tool. High-quality challengers often gauge the political conditions before deciding whether or not to run for office. For instance, Republican Rep. Kevin Cramer jumped into the race against Democratic Sen. Heidi Heitkamp right around when Trump’s job approval rating was hitting a multi-month high. Similarly, it’s not hard to imagine some talented Democrats looking at Tuesday’s results and deciding that their odds for 2018 are as good as it gets.

In the face of all of this data, Republicans have only two factors in their favor: economics and gerrymandering.

Republicans hope that Trump will get credit for a strong economy, and this will in turn give them a boost in the midterm. But economic numbers are far less predictive in midterm elections than they are in general elections, and the solid state of the economy may already be lifting Trump’s numbers above their floor.

And then there’s the House map, where current district lines should theoretically allow Republicans to hold the chamber while losing the popular vote by several points. But that advantage may not be large enough to beat back a Democratic wave. According to some estimates, Democrats would have to win the House popular vote by roughly seven points to take the lower chamber. They’re currently ahead in generic ballot polls by eight points, and the president’s party often loses ground in these polls as the midterm season progresses.

The Lamb-Saccone race isn’t a fluke or an outlier and it doesn’t matter who wins Pennsylvania 18 when the counting (and recounting) is done: Democrats are the favorites to retake the House and this election was another indicator of how much Trump is hurting Republican candidates.