Data: The Downballot, Ballotpedia, AP; Chart: Erin Davis/AxiosRepublican mapmakers thought they were drawing at least a dozen comfortably red districts to protect their House majority.Why it matters: They weren't red enough.In the seven states where Republicans redrew congressional boundaries, the GOP is on track to lose as many as eight seats — rather than gain the 15 it had hoped to pick up.With two exceptions — TX-32 and TN-09 — the pickups Republicans penciled in never materialized.