TALLAHASSEE — Opponents to a proposed constitutional amendment to legalize medical marijuana in Florida gained firepower Tuesday when campaign finance records showed that casino magnate Sheldon Adelson had cut a $2.5 million check to bankroll the opposition effort.

Also Tuesday, a coalition led by the Florida Sheriffs Association announced it was launching a separate statewide campaign to defeat the amendment, known as Amendment 2 on the November ballot.

The contribution by Adelson, owner of the Las Vegas Sands casino empire and a heavy contributor to Gov. Rick Scott's re-election effort, not only juices the antimarijuana movement, it effectively brings the medical marijuana debate into this year's governor's race.

The largest proponent of Amendment 2 has been John Morgan, an Orlando trial lawyer and chief supporter of Scott's top Democratic rival, Charlie Crist.

Morgan, who employs Crist at his law firm, has spent $4 million bankrolling United For Care, the petition-initiative that brought the constitutional amendment to the ballot. He has vowed to spend more money to get the 60 percent majority needed for it to become law.

The newly formed group backed by Adelson, the Drug Free Florida Committee, was started by longtime GOP fundraiser Mel Sembler and his wife, Betty. It has raised $2.7 million so far and its top donors have been primarily Republicans.

Working separately to oppose Amendment 2 is the Florida Sheriffs Association, which has joined the "Don't Let Florida Go to Pot" coalition. The group relies on the same claims that opponents used when they argued before the Florida Supreme Court that the amendment will open the door to "unfettered" access to marijuana because of a poorly worded amendment and loosely regulated system.

The Florida Supreme Court rejected the claims by opponents that the amendment will enable the backdoor legalization of pot in January when it ruled 4-3 that the amendment was narrowly drawn to limit all use of debilitating illnesses.

"This amendment as a matter of fact is a wolf in sheep's clothing," said Polk County Sheriff Grady Judd, president of the Florida Sheriff's Association.

He warned that the proposed amendment is "cleverly written" for "use and abuse," will lead to children legally obtaining marijuana and predicted crime rates will soar.

"You will pay more taxes because it's going to take more policing,'' he said.

Medical marijuana advocates reject the dire predictions as hyperbole and say it is not shared by most Floridians.

Meanwhile, two statewide polls released Tuesday reaffirmed a familiar trend: medical marijuana legalization has overwhelming support across Florida.

A poll by United for Care found that about 70 percent of likely Florida voters support the proposal, while another poll released by Public Policy Polling found about 66 percent support for Amendment 2.

"This support is broad-based and spans the electorate regardless of partisan, regional, or racial lines," pollsters Anzalone Liszt Grove Research/Public Opinion Strategies wrote in an analysis of the United for Care survey.

But Calvina Fay, director of the St. Petersburg-based Drug Free America, which is also funded by Sembler, predicted the amendment would lead to "the Wild Wild West of potent marijuana products." She said "there literally could be drug dealers that could administer this."

The amendment requires doctors and patients to be certified before receiving marijuana through authorized dispensaries. It names nine eligible medical conditions: cancer; glaucoma; human immunodeficiency virus infection, or HIV; acquired immunodeficiency syndrome, or AIDS; hepatitis C, amyotrophic lateral sclerosis, or ALS; Crohn's disease; Parkinson's disease; and multiple sclerosis.

Ben Pollara, campaign manager for United for Care, said opponents "appear to be intent on confusing voters."

"Our opponents can keep trotting out the same discredited talking points for months, but the people of Florida are smarter than that and will approve Amendment 2 this fall," he said. "And poll after poll shows that."

"This Amendment is vulnerable and can be defeated, despite the millions of dollars that have already been spent on it," said Sarah Bascom, Vote No on 2's spokeswoman, in a written statement. "It also means that once Floridians start to learn the truth about the Amendment and are educated on the loopholes, support drops."

Miami Herald reporter Marc Caputo contributed to this report.