Butler County will be split into three different congressional districts if the map issued Monday by the Pennsylvania Supreme Court is kept in place.

Under the map in effect since 2012, the entire county was part of the 3rd Congressional District and represented by Mike Kelly, a Republican. The court earlier this year ruled that map to be unconstitutional, saying in an opinion that it was gerrymandered to favor Republicans.

Pennsylvania's 18 seats in the House of Representatives are all up for election this year. The period to circulate nominating petitions to get on the ballot for the May 15 primary will start next Tuesday.

Butler County is one of four counties that is split into three districts under the court's map, which it dubbed “The Remedial Plan.” Nine counties are split into two districts. The previous map split 28 different counties into multiple districts.

“The Remedial Plan is superior or comparable to all plans submitted by the parties, the intervenors, and amici, by whichever Census-provided definition one employs,” the court wrote in its order. It also wrote that the plan is “superior or comparable” to the various map proposals on the average compactness of districts and that each district in the map has an equal population, plus or minus one person.

Before Monday's announcement, state Republican leaders had vowed to challenge the court's map, saying that the power to redistrict is granted solely to the Legislature by the state's Constitution.

Kelly, who lives in Butler and has district offices in Butler, Erie, New Castle and Sharon, is now in the 16th District. The new 16th District includes most of western Butler County and all of Lawrence, Mercer, Crawford and Erie counties. Eastern Erie County was added to the district, while Armstrong County and southern Clarion County were removed.

Kelly, in a statement Monday night, said:

“My dedicated staff and I are focused on providing the best possible service to the constituents of our district every day, no matter where its boundaries are drawn. That will continue to be my priority as I run for re-election this fall, to keep representing a district that I am still blessed to call home. As of now, I am closely reviewing the entire process that led to this major change to verify that it was in accordance with the Constitution that I swore to uphold.”

According to the maps released by the court Monday, which did not specify municipalities or voting precincts, eastern Butler County including Buffalo, Oakland and Summit townships and Chicora, Bruin and Petrolia boroughs are now part of the 15th District.

Saxonburg is in the 16th District, while Jefferson Township appears to be split between the 16th and 15th.

The new 15th District, which was formerly the 5th District, is represented by Rep. Glenn Thompson of Centre County, a Republican. That district now includes Armstrong and Clarion counties and stretches east to part of Centre County.

Thompson has been in Congress since 2009. Democrats Marc Friedenberg of Centre County, Kerith Strano Taylor of Jefferson County and Wade Jodun of Clinton County had announced campaigns in Thompson's district, though Clinton County and part of Centre County are in the 12th District in the Remedial Plan.

The new map also has part of Cranberry Township in the 17th District, which was previously the 12th District with Republican Rep. Keith Rothfus of Sewickley, Allegheny County.

Rothfus, an attorney elected to Congress in 2012, will likely face a challenger this fall. Ray Linsenmayer, Aaron Anthony, Tom Prigg and John Stoltz, all Allegheny County residents, have previously announced campaigns for the Democratic nomination.

Messages left for Rothfus and Thompson Monday afternoon were not immediately returned.

Two of three Democrats who had announced their intention to challenge Kelly this fall said Monday that they plan to run in the 16th District.

Chris Rieger of Cranberry Township said Monday that he still plans to run in the 16th District, even though the new map may have placed his residence inside the 17th District.

Unlike the state constitution, the U.S. Constitution does not require congressmen to reside in their districts, only in the same state, he said.

Rieger said that he has been campaigning for the past six months in the old 3rd District, which included visits with voters in Butler, New Castle, Sharon, Erie and Kittanning. While Kittanning is no longer part of the district, he said he will continue to campaign throughout the district and introduce himself to voters in the newly added areas.

“Our strategy has not changed,” he said.

Brian Skibo of Hermitage, Mercer County, said in an email that his goal to unseat Kelly and provide new representation for the people of his district has not changed.

“I have lived in Hermitage for around 30 years. It is where my heart is,” he wrote.

Rob Multari, also of Hermitage, could not be reached for comment about his campaign Monday.

Ed Natali, chairman of the Butler County Republican Committee, said Monday that he thought the court's decision and the new map were an unfair political tactic in reaction to Republicans winning the presidency and 13 of 18 House seats for the state.

“Republicans have worked hard for years to win those seats and, quite frankly, provide a better path to liberty, security and freedom for this nation,” he said.

If the changes remain, the committee will help Kelly, Rothfus and Thompson gather signatures and campaign this year. Natali said he expects more Republicans in the county to be motivated to volunteer in light of the redistricting. More information on the committee can be found at butlercountypagop.org.

Mike Coulter, a political-science professor at Grove City College, said that if the U.S. Supreme Court were to intervene, it would need to do so in less than a week because the primary election process is set to start soon.

While some experts have predicted that the changed map will help Democrats take back several districts, challengers are at a disadvantage this year because there is still uncertainty about where they should campaign and what their district will be, Coulter said.

“This is really uncharted territory having all the districts in a state redrawn this close to an election,” he said.

Monday's court order came after Speaker of the House Mike Turzai and Senate President Pro Tempore Joseph Scarnati proposed a new map to Gov. Tom Wolf, who rejected it instead of passing it on to the court. The state Legislature did not vote on any proposed map.

Though Wolf and others submitted their own proposed maps to the court, it created its own map with the help of Nathaniel Persily, a professor at Stanford Law School.

Scarnati and Turzai released a joint statement Monday in which they called the new map the “ultimate partisan gerrymander” and called the situation a “constitutional crisis.”

Wolf in a statement Monday applauded the court and said that his focus now will be to support the Department of State, which will work with the counties during the election process.

The Associated Press contributed to this report.