The Democratic advantage on the generic congressional ballot has slipped over the last few weeks. But Republicans have gradually lost advantages of their own.
Slowly but surely, the considerable structural advantages — like incumbency, geography and gerrymandering — that give the Republicans a chance to survive a so-called wave election are fading, giving Democrats a clearer path to a House majority in November. CONT.
Nate Cohn, New York Times
Recent polls: Generic congressional ballot