Ben Gershman said he was diligent about making sure he registered to vote after moving from Chicago to New York City six months ago.
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He filled in a paper registration form, Gershman said, doing so in person at the state Department of Motor Vehicles.
But that apparently didn't help Tuesday when he went to vote in the state's important primary, which Clinton won by at least 16 percent of the vote.
Gershman, 27, was one of at least 126,000 New York City voters whose registrations were purged, election officials say, which caused mass confusion, frustration and an investigation.
He had repeatedly checked to make sure his registration was up to date, Gershman said, before noticing a couple weeks ago that the online database had marked his registration as invalid.
He repeatedly contacted the Queens County Board of Elections, being told his registration was no good because the combination of his birthdate and his first initial matched that of a voter in the Bronx, prompting the agency to invalidate his paperwork, Gershman said.
"It's the most ridiculous classification system they could use," he told ABC News today.
Eventually, Gershman said, he received email assurances from the Board of Elections that he would be set when he arrived at his polling place in Forest Hills, Queens.
That wasn't the case.
When he arrived at his polling station, his name was not on the registered lists, so poll workers offered him an affidavit ballot instead of the paper ballot.
Gershman, a supporter of Sen. Bernie Sanders, said that because affidavit ballots are typically counted after paper ballots, and sometimes after the election is already called for a candidate, he wanted to make sure his vote was counted early.
In order to do so, however, he had to go the Board of Elections for a court order from a judge before returning to the polling place and filling out the paper ballot, Gershman said.
All told, he said, it took him just under five hours.
"Most people don't have the time in their day or a car like I did to ... go and sit in front of a judge," he added
New York City Board of Elections chief Mike Ryan said Tuesday that there were about 126,000 Brooklyn registrations in question, without addressing other boroughs.
About 12,000 of the people in question had moved away from Brooklyn, 44,000 were declared inactive, and 70,000 were "previously declared inactive" after not voting in two successive elections, he said. The 70,000 people were sent a letter notifying them of the Board of Election's intent to cancel their registrations, although it is unclear whether any of them responded and fought the cancellation, he said.
"Only those people that failed to respond to the intent to cancel notice were, in fact, archived,” Ryan added.
Still, New York City Comptroller Scott Stringer has called for an audit of the Board of Elections, and Mayor Bill de Blasio has echoed those calls.
New York Attorney General Eric Schneiderman announced today that he will be investigating the alleged improprieties. His office received 562 calls -- nearly four times the amount they received during the 2012 election -- and about 140 emails about voting irregularities.
Stringer's office has also created an online portal where voters can share information about their voting experiences.
For Gershman, the process seems like an obvious example of taking away voters' rights.
"It was just absolutely crazy that there's no accountability there,” he said, citing his own experience. “No one seemed to claim responsibility.”
ABC News' Aaron Katersky contributed to this report.