New York state's attorney general has opened an investigation into alleged "improprieties" in the state's presidential primary election on Tuesday that prevented people from voting, starting with a probe of the New York City Board of Elections.

Attorney General Eric Schneiderman said in a statement on Wednesday that he was "deeply troubled by the volume and consistency of voting irregularities" during the primary. Schneiderman's office set up a hotline for voters experiencing issues at the polls on Tuesday, and he said that his office received "more than one thousand complaints."

"If necessary, we will initiate inquiries in additional areas of the state where voting irregularities appeared unusually high," Schneiderman said. "Voting is the cornerstone of our democracy, and if any New Yorker was illegally prevented from voting, I will do everything in my power to make their vote count and ensure that it never happens again."

The attorney general's announcement comes just a day after Election Justice USA, a new watchdog group formed in response to other voter suppression allegations in Arizona last month, filed a lawsuit on behalf of more than 200 New York voters yesterday.

At issue for many of these voters is the state's unusual primary election rules. Like many other states, New York has a closed primary in which only registered Democrats and Republicans can vote in their respective primaries. But New York election laws required that voters declare their party affiliation by October 9, 2015 — six months before Tuesday's primaries — the earliest deadline in the country. An estimated three million voters missed that deadline, unaware that they'd have to join one of the two major parties to vote in their primary at a point when the presidential race looked very different than it does now.

Many voters in the Election Justice USA lawsuit said that they had registered with a party before the deadline, but that their voter registration was either never updated, was entered improperly, or was changed without their consent. Others reported that they had long been registered with a political party in the state, but when they looked up their polling places online just before the primary, they found that they were mysteriously no longer registered to vote.

And that was hardly the only problem in New York on Tuesday. WYNC reported on Election Day that 126,000 Democratic voters in Brooklyn had been purged from the borough's voter rolls since last November, raising concerns from New York City Mayor Bill de Blasio. An elections official there told the radio station that the purge was the result of Brooklyn officials finally catching up with a backlog of voters who had moved or become inactive.

New York City Comptroller Scott Stringer said Tuesday evening that his office would launch an audit of its own into local voting issues, including the voter purge in Brooklyn. Stringer called on the Brooklyn Board of Elections to provide his office with an explanation.

Stringer said that his office would investigate a number of other issues in voting in New York City on Tuesday. The comptroller said his office heard reports of voters who showed up to vote within voting hours only to find that their polling locations were not open. Another 60,000 voters, he noted, were sent notices that the primary was in September rather than April. And many voters complained of uninformed polling workers who could not operate voting machines, erroneously told voters to go to another polling site, and provided New Yorkers with contradictory and often incorrect information, all of which caused confusion and possible voter disenfranchisement on Tuesday.

Vermont Senator Bernie Sanders, who lost the New York primary by a whopping 16 points, raised concerns about the voting issues in a brief discussion with reporters on the tarmac in Burlington, Vermont, late Tuesday night.

"While I congratulate Secretary Clinton, I must say that I am really concerned about the conduct of the voting process in New York state, and I hope that that process will change in the future," Sanders told reporters.

Sanders supporters are making the rounds on social media asking voters who had issues casting their ballots on Tuesday to reach out to the campaign's legal team. VICE News called the phone number they are providing several times on Wednesday, but those calls went to voicemail, purportedly for the Sanders voter hotline.

The Sanders campaign did not respond to a request for comment Wednesday on whether it would participate in the legal battles over New York's voting issues.