For indispensable reporting on the coronavirus crisis, the election, and more, subscribe to the Mother Jones Daily newsletter.

A federal court threw out a Republican challenge to Pennsylvania’s new electoral map on Monday, dealing a blow to GOP efforts to get rid of congressional districts that are friendlier to Democrats. Now all eyes are on the US Supreme Court, the only court that could halt Pennsylvania from holding its 2018 midterm elections under the new map.

In February, the state supreme court put in place a new map after finding that the old map, one of the most extreme gerrymanders in the country, violated the state constitution by favoring Republicans. The federal case, brought by Republican members of Congress from Pennsylvania and two Republican state senators, was a longshot from the start because federal courts have limited authority to weigh in on state court decisions involving state law. This is ultimately what the three-judge panel, all Republican appointees, concluded Monday. “Because fundamental principles of constitutional standing and judicial restraint prohibit us from exercising jurisdiction, we have no authority to take any action other than to dismiss the Plaintiffs’ verified complaint,” the judges wrote.

Republicans trying to get the new map thrown out have one final recourse in the US Supreme Court. The Republican leaders of the state legislature appealed the state case to the Supreme Court last month in a last-ditch effort to preserve the old map. This appeal is also a longshot. It’s the second time state Republicans have tried to get the Supreme Court to intervene. The first time, they were turned away by conservative Justice Samuel Alito.

But the Supreme Court has sat on this appeal for nearly a month now—far longer than expected—causing some experts to speculate that it might consider taking it up. Tuesday is the deadline in the state for filing nominating petitions for candidates in Pennsylvania’s May primaries. That should make it less likely that the justices will force the state to revert back to the old map and scramble candidates’ plans.