The long lines at early voting places have caused the U.S. Justice Department to monitor the rest of early voting in Miami-Dade County, where there have been complaints.
Officials said Friday that Justice Department monitors will check some polling sites to ensure compliance with the 1965 Voting Rights Act. That landmark law prohibits discrimination in elections based on race, color or membership in a minority language group.
Florida Democrats have been calling on Republican Gov. Rick Scott to extend early voting until Sunday to ensure more people can get to the polls. Early voting ends Saturday and Scott has said he will not extend it.
Lines continued to grow at polling places through Central Florida on Friday.
In addition to the tight race between President Barack Obama and former Massachusetts Gov. Mitt Romney for Florida's 29 electoral votes in the presidential contest, there are also a U.S. Senate contest, 11 amendments, a merit retention up-or-down on three Supreme Court justices and scores of local contests for voters to decide.
Florida's Republican-led Legislature reduced the number of early-voting days from 14 in 2008 to eight this year, a move widely perceived as at effort to limit the Democratic voting base in the state. Obama carried Florida in 2008, but is locked in a very close race with Romney in the state, which has the largest amount of electoral votes of any of the swing states.