So what’s changed? Why do we now tilt the House to the Democrats?
Well, part of the reason is simply this: In actuality, not much has changed throughout the cycle. That, in and of itself, is a problem for Republicans.
Election Day is getting closer, and the president’s approval rating is still largely stuck in the low 40s, a big red warning sign that has bedeviled the party of similarly-situated presidents in past midterms. The House generic ballot, which has generally been at around a Democratic lead of between six to eight points, is at the higher end of that range right now. But more importantly for the House battle, for most of this election cycle the generic ballot has shown a consistent Democratic lead that suggests a very competitive battle for the majority. A high number of open seats — the highest number of any postwar election save 1992 — give Democrats many more targets than the GOP (Republicans are defending 41 seats without an incumbent, while Democrats are defending only 22).
Special elections at the state and federal level, sometimes a helpful gauge of what is to come in the midterm, have generally shown Democrats improving on Hillary Clinton’s district-level performance, often drastically. Democrats seem very likely to improve on Clinton’s margin once again in a special election in OH-12 on Aug. 7, the last House special before the midterm, although by how much is a question (an update on OH-12, a race we now call a Toss-up, is included at the bottom of this article).