“The larger point of this exercise is that we would start many more Democratic-held seats as Toss-ups than Republican-held ones even if no district lines were changing.
Overall, these ratings show 211 districts at least leaning to the Republicans, 203 at least leaning to the Democrats, and 21 Toss-ups (19 held by Democrats, two held by Republicans). Splitting the Toss-ups roughly down the middle — let’s say 11-10 Republican — would result in a 222-213 Republican majority, good for a nine-seat Republican net gain and a narrow majority the same size as the one Democrats elected in November.
In other words, Republicans already appear set up to significantly threaten the Democratic House majority, and the net impact of reapportionment and redistricting may make their task easier. Republicans are not guaranteed to win the House next year, but the majority is clearly there for the taking.“
Kyle Kondik, “The House: Democrats Would Have a Tough Slog Even Without Redistricting,” Sabato’s Crystal Ball, 5/20/2021.