The talk in and around Saturday night’s third Democratic presidential debate will, yet again, focus on Hillary Clinton’s electronic data.

But this time the fuss, whether generated by questions from moderators or discussion among the media, will not be about the candidate’s emails or her use of a private server.

Instead, as the candidates gathered in Manchester, New Hampshire, none of them had emerged as winners from the Democratic National Committee’s decision to cut off the Sanders campaign’s access to its voter file for a 36-hour period.

The DNC, the Sanders campaign and the Clinton campaign have all been damaged by one of the most surreal political scandals in recent history.

The drama started on Wednesday morning, when several Sanders campaign staffers discovered that due to a software glitch in the voter file shared by all Democratic presidential campaigns, they could see proprietary data of the Clinton campaign.

The staffers started exploring. In particular, they looked at the support scores the Clinton campaign had compiled in different states. This is proprietary information generated when a campaign, based on polling, modeling and demographic data, estimates the likelihood of a given voter’s support.

The Sanders staffers said that they were only looking at the information in order to test the vulnerabilities of the system. The DNC and the Clinton campaign insisted they were looking to take advantage of the glitch.

It is likely that aspects of both answers are correct. Political staffers are trained to be aggressive and that it’s always safer to beg forgiveness than ask permission. Without any effort, the Sanders staffers were given a rare window into the Clinton campaign’s internal efforts. It would have been hard to resist.

But every search and input on the voter database is logged and the staffers involved were well aware of that. There is no evidence any information was exported out of the voter file. This is not noteworthy. All information is saved within.

The Clinton campaign claimed that “our data was stolen”, but that doesn’t seem to have been the case. What the Sanders staffers did was more like rifling through someone’s belongings and eyeballing each object – before putting it back.

Such actions were unprecedented, though, and should embarrass the Sanders campaign. Even if it wasn’t an intentional hack, it represented remarkably bad judgment.

And then the DNC overreacted and cut off the Sanders campaign’s access to the voter file.

It is hard to overstate how big a deal this was, and how unprecedented such a move is in Democratic politics, and how angry the exchanges on stage in Manchester could be.

The most basic mark of credibility for a Democratic campaign is whether it has bought access to the voter file as administered through NGP VAN, the Democratic party’s quasi-official vendor for voting information. Other companies compete to provide voter information to Democratic candidates but they are almost universally viewed as providing a much lower-quality product.

The only commercial analogy is ketchup. NGP VAN is Heinz and all its competitors are generic brands.

Without access to the voter file, the Sanders campaign was in effect paralyzed. Every list of voters to target comes out of the voter file, whether it is intended to find volunteers, identify supporters or raise money. Every bit of data a campaign collects goes back into the voter file.

It is as essential to a campaign as electricity is to any household. In an unprecedented move, the DNC pulled the plug.

It was a decision that changed the dynamics of the issue. The DNC, which has long been accused of rigging the deck for Hillary Clinton, had intervened without consulting its members. DNC chair Debbie Wasserman Schultz is a longtime Clinton ally and has been criticised for allegedly limiting presidential debates and scheduling them at times when few viewers will be able to watch.

With the decision to shut Sanders out, the story was no longer about allegedly unethical actions by the Sanders campaign. It was about a apparently draconian action by the DNC, with the effect of paralyzing the strongest rival to Clinton.

That prompted the almost unprecedented action by the Sanders campaign of suing the DNC, for $600,000 a day. The complaint focused simply on the fact that the DNC had violated its contract with the Sanders campaign over providing access to the voter file. It had cut off access without any notice of violation of the contract.

The decision to sue also pushed the Sanders campaign into openly accusing the DNC and Wasserman Schultz of trying sabotage their efforts on behalf of Clinton.

What has been an unusually placid Democratic presidential campaign – defined by Sanders’ refusal to criticize Clinton in the first debate by declaring “the American people are sick and tired of hearing about your damn emails” – had turned, suddenly, into a far more divisive conflict.

Many Sanders supporters have accepted the inevitability of Clinton gaining the nomination. The lingering question is whether Sanders will do well enough in early states like Iowa and New Hampshire to force a prolonged primary battle.

But this controversy has inflamed Sanders supporters and created bad blood. One key Sanders supporter is already suggesting the Vermont senator should consider a third-party bid.

No one has come out of this well. The Sanders campaign has undermined its efforts to be seen as a moral crusade against “the millionaire and billionaire class”, through actions by campaign staffers that even seen in the most favorable light were clearly opportunistic and unwise.

The DNC has appeared to be biased and undermined the confidence campaigns need to have in the national party.

And, of course, Clinton is hurt too. After months of dealing with an email scandal from her tenure at as secretary of state, this provides an unwelcome reminder of a problem that she had thought buried after her 11-hour testimony at the congressional hearing on Benghazi in October.

Most of all, it has undermined a previously smooth primary process.

With Donald Trump and the messy Republican primary dominating headlines, Clinton had been able to stay under the radar and take steps towards uniting the Democratic party behind her.

Even in the worst-case scenario, if Sanders won Iowa and New Hampshire, Clinton was still in a dominant position. She would bring her organization resources to bear in March primaries, and pull out a win.

Now, with accusations of theft and sabotage flying around, it’s gotten personal.