Washington (CNN) The Supreme Court has denied a request from Pennsylvania Republicans to block new congressional maps that could tilt several key races in Democrats' favor from being used in the midterm elections.

GOP leaders of the state House and Senate asked the court for an emergency stay blocking the implementation of the maps, which were unveiled last month by the state Supreme Court after it ruled that the previous maps had been gerrymandered in violation of Pennsylvania's Constitution.

Lawyers for House Speaker Mike Turzai and Senate President Pro Tempore Joseph Scarnati argued that the state's high court overstepped its authority in setting a deadline for lawmakers to draw new maps -- and then, when the GOP-led Legislature missed that deadline, producing new maps drawn by an expert selected by the court.

National Republicans and Democrats are paying close attention to the Pennsylvania developments.

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