RICHMOND — Republicans in Virginia’s General Assembly have asked the U.S. Supreme Court to delay a requirement that the state redraw legislative district lines by October, arguing that a lower court erred in finding the districts to be discriminatory against African Americans.

A three-judge panel of the U.S. District Court for the Eastern District of Virginia ruled on June 26 that the lines for 11 House of Delegates districts had been drawn with the purpose of concentrating black voters.

The 2-to-1 ruling was a victory for Democrats, who hope that new district boundaries will help them retake control of the House for the first time in nearly two decades. Last year’s elections wiped out a 2-to-1 GOP advantage in the 100-seat House, leaving Republicans with a narrow 51-to-49 majority.

House Speaker M. Kirkland Cox (R-Colonial Heights) and other GOP leaders on Monday asked the Supreme Court to hear an appeal, arguing that the lower court reached incorrect conclusions.

The district court erred by “ignoring objective evidence of neutral redistricting decisions” and by “discarding first-hand testimony . . . in favor of theoretical and post-hoc expert opinions about motive,” the Republican leadership argued in its motion filed with the high court.

While the case is under appeal, the Republicans asked the court to postpone a requirement that new legislative boundaries be drawn by Oct. 30 for use in next year’s state elections.

Redrawing the map now “will result in voter confusion and disruption to the primary process,” the Republicans argue. “And that is to say nothing of the immense waste of scarce resources” if they win their appeal, the motion continues.

The 11 districts are in Hampton Roads and greater Richmond. But changes to those districts could have a cascading effect, altering the demographics of some of the 22 adjacent districts.

The boundaries were drawn after the 2010 Census, when Republicans controlled the House and Democrats controlled the Senate. With new boundaries, Republicans took control of the Senate and extended their majority in the House — until last year’s wave of Democratic victories in reaction to an unpopular President Trump.