Even a victory in Pennsylvania's 18th House District on Tuesday could be bad news for national Republicans. For starters, the seat has no bearing on the balance on power in the House as Republicans hold a clear majority. And
after a court mandate that new maps go into effect, this seat will likely be eliminated next Congress.
So the real importance of Tuesday's special election pitting Republican Rick Saccone against Democrat Conor Lamb is, instead, what the results say about the strength of each party heading into November's midterm elections.
Republicans may hope that a win will provide them with
an ego boost. But history tells us
it's far more significant to look at the margin between Lamb and Saccone, not at who ultimately wins or loses. And if we're only looking at the margin, it's pretty clear that the result in Pennsylvania's 18th could very likely end up being bad news for Republicans.
We know from past years that the average special election
can tell us a lot about what will occur nationally in the midterms, so long as we look at how much the margins in them deviate from past margins in the district.