In Jacksonville, Fla., Duval County election officials estimated at least 6,000 people turned out Monday on the first day of early voting, but some were hampered by optical vote scanning machines that weren't working properly, The Florida Times-Union reported.

Seven of the 15 optical scan machines were replaced Monday as a result of problems with the machines rejecting ballots, Jerry Holland, Duval County supervisor of elections, told the newspaper.

"We're looking at everything," he said, adding that humidity, the paper or the machines themselves may have been factors. Some voters said they weren't confident their votes were being counted but officials assured them they would be.

The lines for early voting led Florida election officials to predict this year's presidential elections will break records for voter turnout, the Times-Union said.