Either way, the fundamentally balanced House map is the backdrop to the new Texas map. While a few more Republican seats will certainly help the G.O.P., it will take more to give Republicans a major structural advantage in the fight for the House.

States can draw electoral maps for partisan gain, but not if it dilutes the power of voters of color, courts have found.

Some Republican-controlled states are moving to redraw legislative maps to pad their party's narrow House majority in Washington.