Voters cast their ballots for the midterm elections in San Antonio, Texas, U.S., November 6, 2018. REUTERS/Callaghan O'Hare

WASHINGTON (Reuters) - There have been “sparse” reports of voting technology failures in Tuesday’s U.S. elections, but so far they have had no significant impact in preventing people from voting, a U.S. Department of Homeland Security official told reporters.

Earlier, a coalition of more than 100 groups that set up a national hotline for reporting polling irregularities told journalist that problems with voting machines had been reported in at least 12 states by noon ET (1700 GMT) on Tuesday.

There were long waits at some polling stations and technology issues forced some voters to cast provisional ballots. The reports were scattered across the United States, and it was not clear early Tuesday afternoon whether difficulties in any area had potential to swing the dozens of close races for the U.S. Senate, House of Representatives and governor of various states.