Voting problems are reportedly plaguing hundreds of thousands of voters in New York.
Those problems mean many are being turned away from polls and are unable to vote in the primaries.
Many compaints are coming from those supporting Sanders.
CNN reported that reasons for being purged include mail bouncing back from an address, moving in and out of the state or moving from one borough to another, among other reasons.
New York Mayor Bill de Blasio, who is Clinton campaign supporter, is calling on the Board of Elections to "reverse the purge."
"It has been reported to us from voters and voting rights monitors that the voting lists in Brooklyn contain numerous errors, including the purging of entire buildings and blocks of voters from the voting lists," he said in a statement.
Elections board executive director Michael J. Ryan told The New York Times nothing unusual is happening compared to any other election period.
"We’re not seeing anything that is so wildly out of the ordinary as to cause me to be tremendously concerned that there are widespread problems, because there certainly are not," Ryan said.
But some voters have expressed frustration with being turned away and problems with scanning their votes.
"From long lines and dramatic understaffing to longtime voters being forced to cast affidavit ballots and thousands of registered New Yorkers being dropped from the rolls, what's happening today is a disgrace," Sanders spokesman Karthick Ganapathy said.
New York Attorney General Eric Schneiderman's spokesman Nick Benson said Schneiderman's hotline "received more than 700 complaints from voters across (New York state)."
Benson tweeted that in the 2012 general election, around 150 complaints came in.
WCBS reported that New York City Comptroller Scott M. Stringer said he would audit the Board of Elections, partially to find out if Democratic voters were incorrectly removed from voter lists.
“Why is it alleged that 125,000 people have been removed from the voter rolls? Why did 60,000 people receive notices to vote that didn’t have the primary date? Why were people told they were in the wrong polling place time and time again?” Stringer said.
Polls close at 9 p.m.
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