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.

Democratic lawmakers tried to build a case Friday that Republicans in Texas have engineered a rushed and unfair process for redrawing the state's congressional districts in response to a push by President Donald Trump to win more GOP seats that Democrats fear will spread to other states.