RICHMOND, Va.—The Republican speaker of the Virginia House has ruled against a GOP-backed redistricting plan that was muscled through a divided Virginia Senate while a veteran black Democratic lawmaker was attending President Barack Obama's inauguration.

Speaker Bill Howell announced Wednesday that the Senate-approved amendment redrawing state Senate district lines was not germane, or relevant, to a bill making technical changes to state House districts,

On Jan. 21, Senate Republicans blindsided Democrats when they took advantage of the absence of Democratic Sen. Henry Marsh of Richmond to push through a plan creating a new black-majority Senate district and effectively strengthening Republicans' chances in other districts. Marsh was attending the inauguration in Washington.

The move set off a firestorm among Senate Democrats, who'd threatened to deny the Senate's 20 Republicans the necessary 21st vote to advance key initiatives.