HARRISBURG, Pa. >> Pennsylvania’s high court issued a new congressional district map for the state’s 2018 elections on Monday, potentially giving Democrats a boost in their quest to capture control of the U.S. House unless Republicans are able to stop it in federal court.

The map of Pennsylvania’s 18 congressional districts is to be in effect for the May 15 primary and substantially overhauls a congressional map widely viewed as among the nation’s most gerrymandered. The map was approved in a 4-3 decision, with four Democratic justices backing it and one Democratic justice siding with two Republicans against it.

Most significantly, the new map likely gives Democrats a better shot at winning seats in Philadelphia’s heavily populated and moderate suburbs, where Republicans had held seats in bizarrely contorted districts, including one labeled “Goofy Kicking Donald Duck.”

Democrats quickly cheered the new map, which could dramatically change the predominantly Republican, all-male delegation elected on a 6-year-old map.

“It remedies the outrageous gerrymander of 2011, and that’s the important thing, that the gerrymander be over,” said David Landau, the Democratic Party chairman of Delaware County, which was ground zero for the “Goofy Kicking Donald Duck” district. “All that zigging and zagging is all gone, and it makes Delaware County a competitive seat now.”

Republican lawmakers are expected to quickly challenge the map in federal court, arguing that legislatures and governors, not courts, have the constitutional responsibility to draw congressional maps.

Mark Harris, a Pittsburgh-based GOP campaign consultant, echoed the reaction of Republicans in bashing the new product.

“It’s a straight Democratic gerrymander by a Democratic Supreme Court to help Democrats,” Harris said.

Democratic Gov. Tom Wolf, who had backed the court’s decision to throw out the 6-year-old map, lauded the court’s “effort to remedy Pennsylvania’s unfair and unequal congressional elections,” and he said his administration would work to update elections systems for congressional races.

The Democratic-majority state Supreme Court ruled last month in a party line decision that the district boundaries unconstitutionally put partisan interests above neutral line-drawing criteria, such as keeping districts compact and eliminating municipal and county divisions.

The decision is the first time a state court threw out congressional boundaries in a partisan gerrymandering case. Registered Democratic voters and the League of Women Voters originally sued last June.

Republicans appear to face an uphill battle in federal court.

Michael Morley, a constitutional law professor at Barry University in Florida, said federal courts are normally reluctant to undo a state court decision.

“I think it will be major obstacle and a major challenge to get around it,” Morley said.

Pennsylvania’s Republican delegation has provided a crucial pillar of support for Republican control of the U.S. House since 2010.

Republicans who controlled the Legislature and the governor’s office after the 2010 census crafted the now-invalidated map to elect Republicans and succeeded in that aim: Republicans won 13 of 18 seats in three straight elections even though Pennsylvania’s statewide elections are often closely divided and registered Democratic voters outnumber Republicans.

Meanwhile, sitting congressmen, dozens of would-be candidates and millions of voters were beginning to sort out which district they live in barely a month before the candidates’ deadline to submit paperwork to run.

Some races are wide open: There are six incumbents elected in 2016 not running again, the most in four decades. There also is a surge in interest in running for Congress, with Democrats vehemently opposing President Donald Trump.

None of the 12 incumbents was booted into a district with another incumbent, but the new map has immediate implications for some incumbents. Republican Rep. Ryan Costello, whose suburban Philadelphia district was narrowly won by Democrat Hillary Clinton in the 2016 presidential election, is in even more dire straits now that his district would add the heavily Democratic city of Reading.

The new map will not apply to the March 13 special congressional election in the 18th Congressional District between Republican Rick Saccone and Democrat Conor Lamb for a seat left vacant by Republican Tim Murphy’s resignation amid an abortion scandal.

However, Saccone now lives in a new Pittsburgh-area district with Democratic Rep. Mike Doyle, and Lamb lives in another one with Republican Rep. Keith Rothfus. Neither Lamb nor Saccone then would live in the newly redrawn district representing the southwestern-most corner of Pennsylvania.