PHILADELPHIA (CBS) — Pennsylvania Republicans are outraged and are planning to seek U.S. Supreme Court intervention on the state high court decision striking congressional maps. But it could be an uphill battle.

The Pennsylvania Supreme Court ruling is potentially the first final decision requiring a congressional map to be redrawn, but Republicans are calling the ruling “partisan” and the timeline to redraw the map “impossible” and want the nation’s highest court to weigh in.

“It’s very unlikely and highly unusual, this move, and I think it very unlikely to succeed,” says Kermit Roosevelt, who is a professor the University of Pennsylvania Law School and a former US Supreme Court Clerk.

He says because the ruling is based solely on the Pennsylvania Constitution and not on federal law, the doctrine of federalism gives the state high court the final word on the issue. However, Roosevelt says the the US Supreme Court could decide to take the case if Republicans prove that the Pennsylvania Constitutional requirements for maps somehow conflicts with the US Constitution or if the ruling by the state high court somehow interferes with actual conduct of the federal election.

“If [Republicans] can say look this is going to totally throw a federal election into chaos, you can’t let the state supreme Court do that,” says Roosevelt, “maybe the Supreme Court would buy that.”

Republicans issued a statement saying the order only gives the legislature 19 days to redraw maps. They argue courts have given lawmakers four months in other cases. Roosevelt says the US Supreme Court would could decide to provide procedural relief like a temporary stay, possibly giving Republicans more time or blocking implementation of the Pennsylvania high court ruling until, possibly, after the 2018 mid-terms. Roosevelt says it’s highly unlikely the nation’s court would reverse a state Supreme Court decision.

“In a way, the Republicans are asking the US Supreme Court to resolved a dispute between the Pennsylvania Supreme court and the legislature,” says Roosevelt, “this is highly unusual.”

In Bush v. Gore, the Supreme Court weighed in on a state law matter, but only because it was a high state matter dealing with the outcome of the presidential election. Given the timing of this ruling, Roosevelt is not convinced the high court will step in.

“I would be very surprised if the Supreme Court got involved,” he says.

The US Supreme Court recently stayed a North Carolina federal court ruling throwing out a gerrymandered map in that state. But that case dealt with federal, not state law. The high court has yet to rule on a federal law case out of Wisconsin on a map also challenged by Democrats.

Pennsylvania Republicans are expected to file their appeal by the end of this week.

The ruling could impact the outcome in at least five Pennsylvania congressional districts.

This article originally appeared on CBS Philly.