A double-digit GOP lead.
“ And another result is notable: Among those living in congressional districts that are rated as at least somewhat competitive by ABC’s FiveThirtyEight (neither solid Republican nor solid Democratic), registered voters favor Republican candidates by a wide 55-34 percent – nearly as big as the Republican lead in solid GOP districts (+24 points). Democrats lead by 35 points in solid Democratic districts, pointing to a potential overvote where they’re most prevalent.”
https://www.langerresearch.com/wp-content/uploads/1226a1MidtermPolitics.pdf
From the Washington ComPost, no less.