HARRISBURG, Pa. (AP) — The Republican chief justice of the Pennsylvania Supreme Court lashed out Thursday at an effort by a group of GOP state lawmakers to impeach four Democratic justices over their rulings in a congressional redistricting case, calling it "an attack upon an independent judiciary."

Chief Justice Thomas Saylor issued a two-sentence statement on the impeachment drive by 12 Republicans in the state House of Representatives.

"I am very concerned by the reported filing of impeachment resolutions against justices of the Supreme Court of Pennsylvania related to the court's decision about congressional redistricting," Saylor said. "Threats of impeachment directed against justices because of their decision in a particular case are an attack upon an independent judiciary, which is an essential component of our constitutional plan of government."

Last month, Pennsylvania's highest court imposed a new congressional map for the state's 2018 elections after finding the old GOP-crafted map was unconstitutionally drawn. Democrats are hopeful the new district lines will let them flip several seats as part of their effort to reclaim the majority in the U.S. House.

The old map produced three straight election cycles in which Republican candidates won 13 of 18 congressional races, even though Democrats have a 5-4 statewide registration edge and prevailed in 18 of 24 statewide elections during the same period.

The 12 state representatives behind a series of impeachment resolutions, announced Tuesday, are among the 203-member House's more conservative members.

Their prime sponsor, Rep. Cris Dush of rural Jefferson County, denied the effort was an attack on an independent judiciary.

"When the judicial branch fails to follow the constitution, the constitutional answer is impeachment," Dush said. "I believe this action would fulfill our constitutional responsibilities and oaths."

The House Republican leader, however, went on the record in opposition to impeachment.

State Rep. Dave Reed said the Supreme Court was wrong to implement its own map but that "disagreement over the outcome of any particular case should not be grounds for impeachment."

The resolutions seek the impeachment of justices David Wecht, Debra Todd, Christine Donohue and Kevin Dougherty.

Democrats on the elected court hold a 5-2 majority.

After throwing out the old map, the justices gave lawmakers three weeks to enact a replacement that Democratic Gov. Tom Wolf would support. When that didn't happen, the four Democratic justices being targeted for possible impeachment voted to impose their own map.

Saylor and the other Republican on the court voted against throwing out the old map and making the court's own new map the law.

Republican leaders in the Legislature and eight incumbent Republican congressmen turned to federal courts to try to block the use of the new map in this year's elections. But on Monday, both a federal three-judge panel and the U.S. Supreme Court turned down separate requests to put it on hold.

Wolf has called the impeachment effort "an unprecedented and undemocratic attempt to retaliate against the judicial branch."

Lawmakers in at least a half-dozen states have sought in recent years to impeach or otherwise remove judges as a result of controversial decisions — including in some instances over same-sex marriage rulings — but without success, according to the National Center for State Courts.

Supreme Court of Pennsylvania

GOP chief justice slams Republican judicial impeachment move