Backers of a proposed constitutional amendment that would make it harder to expand gambling in Florida have submitted 50,000 valid petition signatures during the past week, with the total now topping 671,000, according to the state Division of Elections website.

The political committee Voters In Charge had submitted 671,893 petition signatures as of early Thursday afternoon, up from 621,763 a week earlier. Supporters of the proposal need to submit 766,200 valid signatures to get the measure on the November 2018 ballot.

The proposal would change the state Constitution and give voters the "exclusive right to decide whether to authorize casino gambling" in the state. It would require voter approval of casino-style games in the future.