The compaign Voters in Charge is running ads to convince people to vote yes on Amendment 3, which ays that only voters can approve new casinos in the future.
Sixty percent of voters would have to say yes in order for it to pass, CBS Miami reports.
State legislators have considered casino gambling proposals in recent years. Disney has opposed efforts to expand gambling in the state. The Seminoles already operate several casinos in the state.
Disney has spent nearly $19.7 million to pass the amendment while the Seminoles have spent nearly $16.8 million.