A summary of computer logs shows that four aides to Vermont Sen. Bernie Sanders' presidential campaign accessed proprietary voter data compiled by the campaign of rival Hillary Clinton and some of the aides saved the voter information.
That's according to a person familiar with the data logs and the breach. The person was not authorized to speak publicly and spoke on condition.
The person said the data represented millions of dollars invested by the Clinton campaign.
The database of voters is maintained by a vendor for the Democratic National Committee, which has temporarily barred Sanders' campaign from accessing it. Sanders' campaign has fired its data director and its campaign manager, Jeff Weaver, and legal counsel was holding a news conference on Friday.
The Democratic National Committee temporarily barred Sanders' presidential campaign from accessing the DNC's voter file after a software error led to the breach, campaign and party officials said on Friday. The person familiar with the breach said the information included lists of voter files from more than 10 early voting states, including Iowa and New Hampshire.
Sanders spokesman Michael Briggs told The Associated Press that the campaign had fired one staff member who reviewed the data, but Briggs blamed a vendor who runs the DNC's voter database for making "serious errors." He said four members of the Sanders campaign had accessed the information but that only the actions of one, the campaign's data director, had risen to the level of a fireable offense.
The DNC maintains an extensive list of voter information and rents it out to campaigns, which update it with their own data. The data allows campaigns to target likely voters and anticipate what issues might motivate them to support a candidate.
It remained unclear how long the Sanders campaign would be barred from accessing the DNC data, but the information could be crucial in his campaign's ability to identify and persuade voters in the kickoff February contests of Iowa and New Hampshire. Sanders has built a strong following among young voters and liberals, but Clinton has maintained a lead in national polls.
The data breach was first reported by The Washington Post. It's the latest dust-up involving the DNC and the three major Democratic presidential campaigns. Former Maryland Gov. Martin O'Malley has complained that the DNC purposely limited the number of presidential debates to six to give Clinton an unfair advantage. The next debate is on Saturday in New Hampshire.
Clinton's campaign declined comment on the incident.