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A new front in the long-simmering voter-data wars opened up Friday following a dispute over security and access between the Sanders campaign, the Democratic National Committee and data and software vendor NGP VAN exploded into public view.

Access to the voter file was suspended for the Sanders campaign after it accessed proprietary Clinton campaign data earlier this week due to an NGP VAN software glitch.

Sanders’ former data chief Josh Uretsky said the breach was made with the intention of showing the DNC and NGP VAN the extent of its security weakness. 

“We were trying to create a clear record of a problem before reporting it,” Uretsky, who was fired by the campaign after the incident, told MSNBC on Friday. “We had to assume that our data was equally exposed and updated reports show that it was, and we wanted to document the extent of the problem.”

He added: “We did not export any records of voter file data. We did establish proof that there was a problem so we could accurate report that up the chain.”

The Sanders campaign said its earlier complaints about NGP VAN’s data security fell on deaf ears. 

“This is not the first time that the vendor hired by the DNC to run the voter file program, NGP VAN, has allowed serious failures to occur,” Jeff Weaver, Sanders’ campaign manager, said in a statement. “On more than one occasion, they have dropped the firewall between the data of competing Democratic campaigns. That is dangerous incompetence. It was our campaign months ago that alerted the DNC to the fact that campaign data was being made available to other campaigns.”

Stu Trevelyan, CEO of NGP VAN, said the Sanders campaign’s complaint to the DNC related to a different platform, not VoteBuilder.

“There was no earlier episode with NGP VAN and the Sanders campaign related to data security,” Trevelyan said. “As stated unequivocally by former Sanders Data Director Josh Uretsky about the October episode, ‘it wasn’t actually within the VAN VoteBuilder system, it was another system.’”

Whatever the intention behind the incursion, the incident pitted the Sanders campaign against the DNC and NGP VAN, its preferred data vendor, in a public spat that could end up in federal court. It also potentially undercuts two main arguments partisan data vendors have made to clients: that data security is better with a partisan shop and that using a partisan vendor will benefit the candidate’s party overall as the data cycles back into the party’s national voter file post-campaign. 

The incident is a clear opening for non-partisan data firms.

“I do think this is a way in which nonpartisan vendors and their views on security are different from partisan vendors,” L2 CEO Bruce Willsie told C&E. “Non-partisan vendors have built their businesses on promises of total security. That’s the only way that these vendors can operate. It’s built into our systems from the ground up.”

Willsie noted that none of their clients risk having their access to data being closed off. “We act as a firewall between the campaigns and anyone who would want to shut off access to their data. It simply can’t happen. They are engaging privately with us,” he said.

CampaignGrid President Jordan Lieberman likened the Sanders situation to being “held hostage” by a third party. 

“This doesn’t just apply to NGP VAN,” he said. “This applies to any highly partisan data source across the board. How do you trust that some group, right or left, won’t say at the last minute, ‘you can’t use our data?’”

By mid-morning Friday, Lieberman’s firm was running sponsored Facebook ads calling the incident “a chilling reminder why candidates and causes must control their own data.”  

NationBuilder also piled on in a statement Friday afternoon.

“All of their data is shared on the same database and even a simple bug can expose data across customers,” Jim Gilliam, the company’s CEO, said in a statement. “At NationBuilder, security is our top priority. We believe that each campaign should work with their own data, which is why we isolate each customer's data into its own database from the very beginning. By doing so, security breaches like this one are nearly impossible with our software.” 

NGP VAN called staff from the Sanders campaign accessing the Clinton campaign’s proprietary data a “brief isolated issue."

"For a brief window, the voter data that is always searchable across campaigns in VoteBuilder included client scores it should not have, on a specific part of the VAN system," Stu Trevelyan, CEO of NGP VAN, said in a statement. "So for voters that a user already had access to, that user was able to search by and view (but not export or save or act on) some attributes that came from another campaign. As soon as we realized that there was an issue, we immediately mobilized our engineers to investigate the source of the issue.”

Still, there was the potential for an earlier incursion, although not through NGP VAN’s system. In an interview with CNN, DNC Chairwoman Debbie Wasserman Schultz confirmed that in October there had been another incident where campaigns’ data was left unsecure by a party vendor. “No one’s information was accessed,” she insisted. 

In Wednesday’s breach, NGP VAN records obtained by Bloomberg indicate that four accounts associated with the Sanders data team, including ones registered to Uretsky and his deputy, Russell Drapkin, searched lists of Clinton’s “likeliest supporters in 10 early voting states, including Iowa and New Hampshire.”

Weaver said the information was not utilized and other disciplinary action may be taken against the staffers involved.

Meanwhile, Wasserman Schultz said the DNC was conducting an audit of NGP VAN and asked the Sanders camp to participate. “This is the only way we can protect the voter file,” she said.

While the standoff over voter file access ended relatively quickly -- by late Friday evening, the DNC had reversed course and restored access for the Sanders campaign -- expect the incident to continue to reverberate for NGP VAN, and impact the host of other companies in the political data world.   

This article has been updated.