SAN ANTONIO (AP) -- An attorney defending Republican-drawn voting maps in Texas has told a federal court there are "insurmountable" differences preventing a compromise with minority rights groups.

The stalemate Tuesday left the date of the Texas primary in doubt. A three-judge panel didn't immediately address whether Texas can still hold an April primary during a standing room-only court hearing in San Antonio.

The primaries are currently set for April 3, but that date is widely considered no longer realistic.

The Texas attorney general's office and minority groups instead spent Tuesday morning laying out obstacles to a compromise on voting maps for the 2012 elections. David Mattax, an attorney for the state, suggested that differences on one map that draws four new congressional seats in Texas can't be resolved.

(Copyright 2012 by The Associated Press.  All Rights Reserved.)