Voters in Florida, a key battleground, have reported have encountered aggressive, intimidating behaviour, according to an independent group monitoring election issues nationwide.
"In Florida we continue to receive a substantial amount of complaints about voter intimidation," The Washington Post quoted Kristen Clarke, president of Lawyers' Committee for Civil Rights Under Law, which is running an independent effort to field voter complaints and questions, as saying.
Clarke said her group received reports from Miami-Dade County of "yelling, people using megaphones aggressively".
In Jacksonville, Florida, Clarke said: "An unauthorised individual was found inside a polling place."
Clarke said her group has received reports from about 80,000 voters since the beginning of early voting and expects the figure to reach 175,000 reports by the time the polls close.
With inputs from IANS.