Democratic Party candidate Bernie Sanders has been suspended from viewing his party's voter records after it was discovered that one of his staffers viewed confidential information from Hillary Clinton's campaign. The information was accessed on Wednesday, BuzzFeed News reports, when a bug in the technology used by NGP VAN to provide voter lists for the various Democratic candidates inadvertently showed internal voter data for all campaigns for around 30 minutes. The Sanders campaign reportedly discovered the bug and informed NGP VAN about it, but not before someone on the Sanders side accessed data from the Clinton campaign.

The aide reportedly responsible for accessing the information has been fired, but the Democratic National Committee says it won't restore access to the voter file until the Sanders campaign can show that it has deleted all the data it accessed. NGP VAN keeps a centralized list of voters that it shares with Democratic campaigns. Those campaigns are then free to add their own information, such as voter affiliations, political leanings, and preferences. The differing versions of the file are kept supposedly kept separate by firewall, but in this case, it appeared that firewall failed.

Speaking to BuzzFeed News, Michael Briggs — communications aide for the Sanders campaign — turned the blame on NGP VAN. "Sadly, the vendor who runs the DNC's voter file program continues to make serious errors," he said, referring to "more than one occasion" when Democratic campaigns were inadvertently able to access each others' data. "Our campaign months ago alerted the DNC to the fact that campaign data was being made available to other campaigns," he said. "At that time our campaign did not run to the media, relying instead on assurances from the vendor."

Luis Miranda, the DNC's communications director, said the committee was "working with our campaigns and the vendor to have full clarity on the extent of the breach, ensure that this isolated incident does not happen again, and to enable our campaigns to continue engaging voters on the issues that matter most to them and their families." Stu Trevelyan, head of NGP VAN, downplayed the incident, saying it was "fairly short in duration," and that "by lunchtime, it was resolved."

But that won't be much comfort for Bernie Sanders. With only six weeks to go until the Democratic primaries, Sanders' campaign will need to prove that it has expunged any data it accessed from the Clinton campaign as soon as possible, or face going into one of the most important stages of the election at a severe disadvantage.