HARRISBURG, Pa. — The Pennsylvania Supreme Court struck down the state’s widely criticized congressional map Monday, granting a major victory to Democrats who alleged the 18 districts were unconstitutionally gerrymandered to benefit Republicans and setting off a scramble to draw a new map.

In the Democratic-controlled court’s decision, the majority said the boundaries “clearly, plainly and palpably” violate the state’s constitution and blocked the boundaries from remaining in effect for the 2018 elections with just weeks until dozens of people file paperwork to run for Congress.

The justices gave the Republican-controlled Legislature until Feb. 9 to pass a replacement and Democratic Gov. Tom Wolf until Feb. 15 to submit it to the court.  Otherwise, the justices said they will adopt a plan in an effort to keep the May 15 primary election on track.

The decision comes amid a national tide of gerrymandering cases, including some that have reached the U.S. Supreme Court.

Democrats cheered the decision to toss out a Republican-drawn map used in three general elections going back to 2012. The map, they say, gave Republicans crucial help in securing 13 of 18 seats in a state where registered Democratic voters outnumber Republicans 5 to 4.

“We won the whole thing,” said David Gersch of the Arnold & Porter Kaye Scholer law firm in Washington, D.C., which is helping represent the group of registered Democrats who filed the lawsuit last June.

The defendants — top Republican lawmakers — said they would ask the U.S. Supreme Court this week to step in and put the decision on hold. The state court’s decision lacks clarity, precedent and respect for the constitution and would introduce chaos into the state’s congressional races, they said.

The Senate’s top Republican lawyer, Drew Crompton, called the timeline to draw new districts “borderline unworkable,” but said Republicans will do everything they can to comply.

The decision has immediate implications for the 2018 election, meaning that 14 sitting members of Congress and dozens more people are planning to run in districts they may no longer live in. The deadline to file paperwork to run in primaries is March 6.

It also has implications for GOP control of Congress, since only Texas, California and Florida send more Republicans to the U.S. House than Pennsylvania.

Republicans who controlled Pennsylvania’s Legislature and governor’s office following the 2010 census broke decades of geographical precedent when redrawing the map, producing contorted shapes.