The Pennsylvania special election shows the 2018 House battleground is enormous

Set aside who actually won the Pennsylvania special House election between Democrat Conor Lamb and Republican Rick Saccone — which we might not know for a while yet — and look at the big picture: Republicans are in big, big, big trouble.

Donald Trump won Pennsylvania’s 18th Congressional District by nearly 20 points. The House special election will be decided by less than a percentage point, in either Lamb or Saccone’s favor (and maybe after a recount?). That is a huge swing toward Democrats.

When you take a step back and look at the 2018 race for the House, you realize: There are more than 110 Republican-held House districts that Trump won by less than he won in the district where the Republican House candidate just effectively tied with the Democrat.

Strategists and election analysts on Twitter couldn’t quite agree on exactly how many districts — 114? 118? 119? — but the number is, by all accounts, greater than 110. A few months ago, you wouldn’t have heard Democratic operatives, even at their most optimistic, describe the 2018 battleground as that big. (As of last month, Democrats had just expanded their battleground map to 101 seats.)

There are the districts Hillary Clinton won, of course, but there are also the suburban, classically Republican districts where Trump has soured the electorate, and those white working-class districts with Obama-Trump voters.

This comes with plenty of caveats. This was a special election. Republican incumbents are going to be stronger than Republicans in an open seat like the Pennsylvania 18th. Conor Lamb was a particularly strong Democratic candidate, and Rick Saccone might have been an unusually weak Republican nominee.

But still: Democrats need 24 seats to reclaim the House majority. If Tuesday night is any guide, it looks like they will have a lot of opportunities to get them.