The Pennsylvania Supreme Court ruled Monday that the state's congressional maps are unconstitutional.

The decision came after a lawsuit was filed by a group of Democratic voters who argued the districts were gerrymandered to benefit Republicans.

Though registered Democrats outnumber Republicans by 5 to 4 in the state, 13 of 18 House of Representatives seats currently are held by Republicans, they argued.

The term gerrymandering is used to describe electoral districts that are intentionally drawn to give advantage to one political party.

The state Legislature and governor must come up with a new map, that isn't gerrymandered, before the May primary elections, the court said.

According to the order issued by the court Monday afternoon, the Legislature must come up with a fairly drawn map by Feb. 9 and the governor must approve the map and send it to the court by Feb. 15.

If state officials do not provide a new map, the court will “expeditiously” adopt a plan based on the “evidentiary record developed in the Commonwealth Court,” the order said.

The order also stated that the new map must have congressional districts that are composed of compact and contiguous territory, as nearly equal in population as practicable and don't divide any county, city, township or borough, except where necessary.

The current maps were devised in 2012, using data from the 2010 census, by a five-person Legislative Reapportionment Commission.

All of Butler County is included in the 3rd Congressional District and is represented by Rep. Mike Kelly.

“Today's misguided decision by the Pennsylvania State Supreme Court is an unfortunate example of the judicial branch inserting itself into the core functions of the legislative branch,” said a statement issued Monday from Kelly's office by the state Republican congressional delegation.

“Today's congressional maps were drafted and approved by both Republicans and Democrats,” the statement continued. “It also comes on the eve of a midterm election. An orderly electoral process is an essential function of our democracy.”

Several of the state representatives for Butler County said Monday that they were waiting to see how political leadership would respond to the ruling and whether the ruling could be appealed to the federal Supreme Court.

State Rep. Tedd Nesbit, R-8th, said that he believes the decision to be an overreach by the court.

“They shouldn't be able to redraw the map. Under what authority would they be doing that?” Nesbit said.

Nesbit said that he doesn't believe the congressional map to be unconstitutional.

“It has been used in four election cycles and now just because people are upset with the results of the election, they are challenging the process,” he said.

State Rep. Jeff Pyle, R-60th, said that the court's order might conflict with a federal Supreme Court ruling in 2013 that approved the revised maps.

There isn't a lot of leeway when it comes to drawing the districts according to the state's rules, he said.

“It's mostly done by computer, they take all the registrations and plug them in and figure out what meets all the requirements,” he said.

State Sen. Don White, R-41st, said he thinks redistricting is a complicated issue without an easy answer.

He said redistricting has both helped and hurt him over the course of his career.

“I honestly don't expect this problem to be solved on a short-term basis, unless the Supreme Court takes total control of these maps,” he said about the court-imposed deadline.

Gov. Tom Wolf, in a statement Monday afternoon, said that his administration is reviewing the court's order.

“I strongly believe that gerrymandering is wrong and consistently have stated that the current maps are unfair to Pennsylvanians,” he said.

The deadline to file paperwork to run in primaries for House seats in Pennsylvania is March 6. Kelly has already announced his bid for re-election.

The U.S. Supreme Court also is weighing whether redistricting can be so partisan that it violates the U.S. Constitution, in cases from Maryland and Wisconsin. The high court has never struck down an electoral map as a partisan gerrymander.

The Associated Press contributed to this report.