WASHINGTON — President Trump added his voice on Saturday to the continued conservative outcry over the court-ordered redistricting of the Pennsylvania congressional map, calling the decision “very unfair to Republicans and to our country.”

“Democrat judges have totally redrawn election lines in the great State of Pennsylvania,” Mr. Trump wrote on Twitter. “This is very unfair to Republicans and to our country as a whole. Must be appealed to the United States Supreme Court ASAP!”

The Supreme Court this month denied a request from Pennsylvania Republicans to stop the state’s highest court from requiring lawmakers to redraw the map of the state’s 18 House districts. The new map, released by the state court this past week, effectively eliminates the Republican advantage in Pennsylvania, endangering several incumbent Republican seats and bolstering Democrat standings in two open races.

Pennsylvania is typically a swing state, and the new map, if it stands, could play a crucial role in efforts by the Democratic Party to gain control of the House in the midterm elections.