In a huge blow to the Bernie Sanders campaign, the Democratic National Committee claims that they caught Team Bernie accessing Hillary Clinton’s voter files in direct violation of their party rules, and they’re suspending him from voter data access for it.

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More from CNN:

The Democratic National Committee has suspended Sen. Bernie Sanders’ presidential campaign from accessing its voter database after the campaign took advantage of a software error to access Hillary Clinton’s confidential voter information.

The suspension is a setback for the Vermont senator because the database is a goldmine of information about voters nationwide. Campaigns usually use that data to plot their next moves.

The DNC database keeps the information gathered by different campaigns separated by a firewall.

But the data systems vendor that runs the program dropped the firewall for a brief period Wednesday, during which time the data was accessed.

The Washington Post was the first to report the incident.

According to the Sanders team, one staffer has been fired.

“That behavior is unacceptable and that staffer was fired immediately,” Sanders’ spokesman Michael Briggs said.

The New York Times said the staffer was the campaign data director. Searches were run from four user accounts while data from Clinton’s campaign was exposed, the Times said. But it’s difficult to say what that means, since one person could have had more than one user account.

The Sanders campaign will remain suspended until it provides the DNC with a full explanation of the episode and provides proof that any accessed data has been discarded.

With the Iowa caucuses and New Hampshire primaries now less than two months away, this suspension will likely be an obstacle for the Sanders campaign.