MADISON, Wis. (CN) – Democrats challenging redistricting in Wisconsin filed an amended lawsuit Friday in an effort to persuade the U.S. Supreme Court that they have legal standing to bring their claims.

In June, the Supreme Court punted on the closely watched gerrymandering case in Wisconsin and declined to rule on the merits. But the justices invited the Democratic voters to prove that Republican redistricting in the Badger State had diluted their voting power and violated their constitutional rights.

On Friday, the Campaign Legal Center filed the amended lawsuit that builds on the claims of the original 12 voters. Now, 40 voters in 34 legislative districts have joined the suit in Madison federal court.

They say that the complaint now makes clear that the Wisconsin State Assembly’s 2011 redistricting plan violates the First and 14th Amendments of the U.S. Constitution.

Calling the Republican plan “one of the worst partisan gerrymanders in modern American history,” the voters say that the map led to a red wave that allowed GOP politicians to land 60 of the state assembly’s 99 seats, even as Democrats won the statewide vote.

“The evidence is overwhelming that the current plan was adopted to achieve precisely that result,” the lawsuit states states. “This kind of partisan gerrymandering is both unconstitutional and profoundly undemocratic.”

Governor Scott Walker’s press secretary Amy Hasenberg said in a statement, “We remain confident the maps will continue to be upheld as they were earlier this year when the Supreme Court ruled unanimously in favor of the State of Wisconsin.”

Members of the Democratic assembly filed a separate lawsuit that asks the court to consolidate the claims, the Milwaukee Journal Sentinel reports.

The amended complaint says the voters have shown district-specific harm to the plaintiffs to establish their claims. The whole map weakens their voting power and should be thrown out, they argue.

In a statement, University of Wisconsin-Madison law professor and lead plaintiff Bill Whitford said voters have been casting their ballots under an unconstitutional map since the 2012 election.

“We followed the Supreme Court’s roadmap and entered additional evidence into the record that strengthened our case, showing real harms to voters caused by lawmakers who chose their own partisan self-interest over the good of the state. We hope to return to the Supreme Court as soon as possible,” Whitford said in a statement.

The plaintiffs are seeking a declaration that the map is unconstitutional, and an injunction that prevents its use in the 2020 election.