The citizen initiative is being pushed by billionaire health care executive Mike Fernandez, who left the Republican Party after President Donald Trump‘s election.

If passed by 60 percent of voters, Amendment 3 would allow all voters, including those who have no party affiliation, to cast ballots in Florida’s August primaries for state legislative seats and statewide posts such as governor. The top two candidates, regardless of party affiliation, would advance to the November general election. The system would be similar to California‘s. It would not apply to federal races.

The Republican Party of Florida, which has controlled the Legislature and governor’s mansion for 22 years, last week voted to oppose Amendment 3 and asked GOP leaders to speak out against the measure. Party Chair Joe Gruters, who has called the proposed amendment misleading, said Republicans are “moving ahead with plans to try to take it down.”

The League of Women Voters last week rescinded its endorsement of the measure, saying it would suppress minority voters and candidates from minority communities.

Neither proponents of Amendment 3 nor their political opponents have put together an organized, paid campaign to pass or defeat the initiative, which will be placed at the end of a long November ballot.

But a sustained messaging campaign on social media and in the press could be enough to take down Amendment 3, which requires a supermajority to pass. The criticism by Black lawmakers that the initiative is detrimental to minorities could be especially damaging to the initiative.

Their main argument is that opening up primaries to Republicans and independent voters will dilute minority voting strength and lead to fewer Black and Hispanic candidates winning. About a third of the 120-member Florida House is either Black or Hispanic. Twelve of Florida‘s 40 senators are Black or Hispanic. Gov. Ron DeSantis and the three Cabinet members are white.

Backers of the measure have said that arguments offered by opponents are flawed because they don’t consider how people registered as independents or with minor parties would vote in a primary.

“Today approximately one million Black and Hispanic voters are denied the ability to vote in meaningful election simply because they refuse to be forced to join a political party,” said Glenn Burhans, chair of All Voters Vote, in a written statement. “That denial of the right to vote is wrong. The All Voters Vote amendment will ensure that no registered voter can be denied the right to vote in these taxpayer-funded elections.”

And the open primary system in California hasn’t diminished minority participation in that state, supporters of Amendment 3 say. Sen. Kamala Harris, the first Black woman to be nominated by a major party for vice president, won her election to the U.S. Senate through such a system.

Sean Shaw, a former legislator who opposes the amendment, said it was wrong to compare California to Florida because Florida's registered voters are almost evenly split among the two main political parties.

Fernandez, saying he feared the rise of of political extremism in the United States, spent more than $6 million of his own money to get the amendment on the ballot. But he has not made any significant investments to get the measure passed. Campaign records show that he has spent slightly more than $79,000 this year.