TALLAHASSEE, Fla. (AP) — Even as close to 2 million ballots have been cast, a lawsuit filed Tuesday asks the Florida Supreme Court to nullify a proposed constitutional amendment that would open primaries to all voters regardless of party affiliation.

Incoming Republican House speaker Chris Sprowls and Democratic Sen. Janet Cruz expressed support for the lawsuit in a joint press conference, saying that the proposal would hurt minority representation in government.

“This can do irreparable damage to our political process. This is the political equivalent to a battle royal. Nobody understands who’s going to be left out, nobody understands the damage that is going to be done to the process and who’s going to be disenfranchised, which is why it shouldn’t go into the constitution,” Sprowls said.

The ballot question would style Florida elections similar to those in California. In Florida, all candidates for the state Legislature, Cabinet and governor would appear on the same primary ballot and then the top two candidates would move on to the general election. That could mean two Democrats or two Republicans face each other in the general election.

The group All Voters Vote gathered petitions to put the proposal on the ballot. It would need 60% approval to pass.

Supporters say the current system produces the most politically extreme candidates in the general election because independent voters don't haver a say in primary elections. Florida has more than 3.8 million voters who aren't registered with either major party, or about 27% of Florida's more than 14 million voters.

The Supreme Court approved the ballot language in December. Anne Corcoran, who is representing voter Glenton Gilzean in the lawsuit, said it's unusual to ask the court to reverse a previous opinion. But she said studies that have come out since the opinion find that minority representation would be hurt if it passes.

In a written statement, All Voters Vote Chairman Glenn Burhans said those studies were “a sham report based on flawed and misleading data.”

“This is a grotesque misuse of the courts for a political stunt; the claims have no merit,” Burhans said.

The lawsuit comes as Floridians have already cast 1.8 million ballots by mail. It asks that votes for and against the proposal not be counted.

“If passed this amendment will hurt minority representation and lead to more mudslinging and political chaos,” Cruz said. “Simply put, this amendment is a real threat to true representative democracy. ”