For the second year in a row, Florida parents are preparing to battle in Tallahassee against the powerful school-choice lobby over the so-called parent trigger bill.

And the issue — enabling parents to convert traditional public schools into charter shools — is simmering in Miami-Dade.

Two attempts — one failed and one just starting — have tried to use a process already on the state books: Parents and teachers can hold a vote to convert a school; if half of them approve, an application can go to the school board.

In Key Biscayne, Manuel Cambó and Hector Ceballos want to hold a vote to convert their children’s school, the Key Biscayne K-8 Center, into a charter. The school has an A-grade from the state, but is overcrowded and has aging buildings. While Cambó’s brother, Robert Cambó, has developed charters and leases to charters in South Florida, Cambó says his family isn’t seeking to profit. Their vision is to turn the school into a nonprofit charter, run by parents and professional advisors, with new buildings and the same staff.

The two dads are proceeding slowly with the help of attorney Jorge Cruz Bustillo, who was appointed to the Florida Elections Commission by former Gov. Jeb Bush. They fear fallout for the school’s administrators, after what happened at another school.

At Neva King Cooper Educational Center in Homestead, the principal and assistant principal recommended a charter conversion in February. The school’s advisory board first endorsed the idea, then took it back. Complaints that the school administrators intimidated potential voters prompted an internal probe. Principal Alberto Fernandez and Assistant Principal Henny Cristobal were demoted to jobs at the school district’s mail room and motor fleet.

They are contesting their demotions with the state Department of Education, with the aid of a Lake Wales attorney with ties to charter schools. The district’s assistant chief auditor, Julio Miranda, told the state he “guarantees there is no retaliation.” The state has reviewed the case but not yet ruled.

“These demotions have sent out a chill across the whole district that no employee better send in a letter asking for this vote,” Bustillo said. In an email, the Miami-Dade School Board’s attorney, Walter Harvey, denied his request to negotiate a balloting process, calling it “premature, unauthorized, and contrary to state law.”

Charter schools receive tax dollars but are run by management companies instead of the locally elected school board. If a public school becomes a charter, the district loses state funding for those students — about $6,120 in 2011-12 in Miami-Dade.

The state Board of Education wants to increase the number of charters in Florida by 60 percent over the next six years. Currently, Florida has more than 500 charters, with just over one in five of those in Miami-Dade County.

Only 20 current charters in Florida — none of them in Miami-Dade or Broward — were converted from traditional public schools.

The parent trigger law, which failed in the last legislative session, would have enabled parents at underperforming schools to create a turnaround plan, with charter conversion as an option. State Rep. Michael Bileca, R-Miami, filed the bill, called Parent Empowerment in Education. Another bill is expected next session, according to Florida PTA, which opposed it.