Costello had been considering the decision since February, when the Pennsylvania Supreme Court drew a new map to replace a gerrymander that Republicans put into place seven years ago. The 6th District, which had cut through three suburban counties in an L-shape, was reshaped to include all of Costello’s Chester County and part of Berks County.
That change turned a district that had narrowly backed Democrat Hillary Clinton for president into one that had given her a 10-point margin of victory over Donald Trump. Before Costello’s decision, the Cook Political Report rated the 6th District a “toss-up,” and the congressman had called on state legislators to impeach the judges who drew the new map. (Pennsylvania elects judges in partisan elections, and the majority that ruled on the map was mostly composed of Democrats.)
“The state Supreme Court, in a matter of a week or so decided to invalidate the map,” Costello said on Sunday night. “The first time in the history of the republic that a state Supreme Court has done that.”