WASHINGTON — (CNN) Bernie Sanders’ campaign on Friday threatened to take the Democratic National Committee to federal court if the party organization doesn’t restore the campaign’s access to a crucial voter database.

The internal warfare exploded after the DNC cut Sanders off from the database and charged that the Vermont senator’s presidential campaign exploited a software error to improperly access confidential voter information collected by Hillary Clinton’s team.

Coming the day before a Democratic debate, the developments fueled a long-held belief in the Sanders camp and among his allies that the DNC has stacked the deck against them in favor of Clinton.

The revelation poses a setback for Sanders, who is mounting a liberal challenge to Clinton. The database is a goldmine of information about voters and being blocked from it could complicate Sanders’ outreach efforts. The timing is also challenging, just weeks before Clinton and Sanders are slated to compete in the Iowa caucuses.

At a press conference in Washington on Friday, Sanders campaign manager Jeff Weaver accused the DNC of trying to sabotage the campaign and he vowed to fight the DNC in federal court if the campaign’s access to the data is not quickly restored.

“The DNC, in an inappropriate overreaction, has denied us access to our own data,” Weaver said. “In other words, the leadership of the Democratic National Committee is actively trying to undermine our campaign … If they hold our data hostage, we will be in federal court this afternoon seeking immediate relief.”

He added, “The DNC is clearly acting in a heavy-handed way, in an unprecendented way. I would like to see another instance where a presidential campaign had their data — their own data — withheld under similar circumstances.”

Weaver said the problem with the database’s security dated back to October.

“We were very concerned that large amounts of our own data was being downloaded and we contacted the DNC to remedy the situation,” he said. “We talked to them and we were assured that this was going to be taken care of. But apparently they are not competent in terms of maintaining the security of their data between the campaigns.”

The DNC, however, had a very different story.

Shortly after Weaver’s press conference, DNC chairwoman Debbie Wasserman Schultz said suspending the Sanders’ campaign’s access was the only way to ensure the voter file was properly safeguarded.

“That is the only way that we can make sure that we can protect our significant asset that is the voter file and its integrity,” Wasserman Schultz said on CNN.

She charged that “multiple staffers” from the Sanders campaign downloaded information that they did not have the right to collect.

“They not only viewed it, but they exported it and they downloaded it,” Wasserman Schultz told CNN’s Wolf Blitzer. “We don’t know the depth of what they actually viewed and downloaded. We have to make sure that they did not manipulate the information.”

She added, “That is just like if you walked into someone’s home when the door was unlocked and took things that don’t belong to you in order to use them for your own benefit. That’s inappropriate. Unacceptable.”

The DNC also sent out a strongly worded message from Wasserman Schultz to its members accusing the Sanders campaign of improper conduct.

“… over the course of approximately 45 minutes, staffers of the Bernie Sanders campaign inappropriately accessed voter targeting data belonging to the Hillary Clinton campaign,” Wasserman Schultz said in the message.

“Once the DNC became aware that the Sanders campaign had inappropriately and systematically accessed Clinton campaign data, and in doing so violated the agreement that all the presidential campaigns have signed with the DNC, as the agreement provides, we directed NGP VAN [the vendor that supplies access to the database] to suspend the Sanders campaign’s access to the system until the DNC is provided with a full accounting of whether or not this information was used and the way in which it was disposed,” she added.

Josh Uretsky, the Sanders national data director who was fired Thursday by the campaign for accessing the database, told CNN Friday that he was not trying to access Clinton’s data and denied that any of the information had been downloaded, as Wasserman Schultz claimed.

“We knew there was a security breach in the data, and we were just trying to understand it and what was happening,” Uretsky said.

He said that none of the data the Sanders campaign accessed on Wednesday “left the system that day” and denied that he or his staff “downloaded any individual level voter file data.”

Uretsky said he and his team downloaded only phone numbers but did so to alert the DNC and NGP VAN that the Sanders campaign was aware the data wasn’t being properly protected.

“We knew that what we were doing was being recorded,” he told CNN. “We didn’t try to be sneaky at all. They can argue that we shouldn’t have done it but we did not in any way try to deceive them. We created the records of it having been done and we did to make any attempt to use it for strategic purposes.”

NGP VAN issued a statement Friday saying the DNC had instructed the company to remove the Sanders campaign’s access to the database.

“We are confident at this point that no campaigns have access to or have retained any voter file data of any other clients; with one possible exception, one of the presidential campaigns,” the company said, adding that it was investigating the breach and would report back to the DNC.

“Our team removed access to the affected data, and determined that only one campaign took actions that could possibly have led to it retaining data to which it should not have had access,” the statement continued.

The database breach was first reported by The Washington Post. Clinton’s campaign hasn’t commented on the incident.

Sanders supporters and liberal groups have reacted to the news of Sanders’ campaign being punished by questioning the neutrality of the DNC, hinting that the body is in the tank for Clinton.

“The Democratic National Committee’s decision to attack the campaign that figured out the problem, rather than go after the vendor that made the mistake, is profoundly damaging to the party’s Democratic process,” said Charles Chamberlain, executive director of Democracy for America, a liberal group that endorsed Sanders this week.

“DNC leaders should immediately reverse this disturbing decision before the committee does even more to bring its neutrality in the race for President into question,” he added.

Weaver, the Sanders campaign manager, said of the DNC, “In this case, it looks like they are trying to help the Clinton campaign.”

“We are taking on the establishment and I’m sure there are people within the Democratic establishment who are not happy about the overwhelming success that Bernie Sanders is having all across this country,” he added. “But we are determined to win this campaign and we’re going to win this campaign by talking about the issues that are important to the American people. To do that we are going to need our data, which has been stolen by the DNC.”

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