Sen. Bernie Sanders made good on his threat to sue the Democratic National Committee on Friday afternoon, as the fight over a data breach committed by his campaign escalated into a broader battle with the Democratic Party’s establishment.

Sanders’ suit seeks to regain access to a voter database that his campaign says is crucial to his ability to raise funds and reach voters. The DNC cut off the campaign’s access Thursday after it was discovered that Sanders’ campaign staffers had improperly looked at private voter files that belonged to Hillary Clinton’s campaign.

The Sanders suit claims that its contract to use the database cannot legally be terminated without 10 days' written notice, that its access to Clinton’s data was “inadvertent,” and that the larger problem is the fault of the third-party vendor, NGP VAN, which left the data vulnerable.

“The Campaign should not be punished for the carelessness of the DNC and its third-party vendor,” Sanders’ attorneys Benjamin J. Lambiotte and Sean C. Griffin wrote in the suit, filed just before the close of business.

The attorneys argued that the Sanders campaign is “hamstrung” without the voter database.

“The financial damage caused by the loss of donations is estimated to be approximately $600,000.00 a day,” they wrote. “However the damage to the Campaign’s political viability, as a result of being unable to communicate with constituents and voters, is far more severe, and incapable of measurement.”

Here's a link to the suit: https://berniesanders.com/wp-content/uploads/2015/12/Bernie2016vDNCComplaint.pdf

Read the lawsuit here.

The campaign of Bernie Sanders is threatening to sue the Democratic National Committee after it cut off his access to a crucial voter database. The DNC says it made the move because some Sanders staffers had been discovered looking at private files that belonged to Hillary Clinton's campaign. The breach puts a spotlight on the outsize role such voter data files play in today’s politics.

So why, exactly, is this such a big deal? Here are a few questions and answers breaking it down:

Vermont Sen. Bernie Sanders’ campaign threatened to take the Democratic National Committee to federal court this afternoon unless it releases voter data that campaign manager Jeff Weaver called “the lifeblood of this campaign.”

“This is taking our campaign hostage,” Weaver, accompanied by a campaign attorney, said at a fiery news conference outside the Capitol Hill row house that Sanders uses as his headquarters. “The leadership of the Democratic National Committee is now actively trying to undermine our campaign.”

The DNC has denied Sanders’ campaign access to its wide database of voter information while it investigates a breach by the Sanders campaign that allowed staffers to view data owned by Hillary Clinton’s campaign.

The news conference appeared to be an effort by Sanders to recast his campaign’s violation as a clash between party officials and his insurgent campaign.

Weaver maintained that firing the staffer responsible for breaching Clinton’s voter data shows the Sanders campaign’s high ethical standards.

“We are running a clean campaign,” he said. “We don’t need dirty tricks.”

But his contrition was brief compared with his fierce attack on the DNC and what he alleged as “dangerous incompetence” in the party’s data operation.

He said the campaign found and reported security gaps that left its own data vulnerable in October and demanded repairs from the DNC and its vendor. He said the campaign is “very confident” that its own data was “lost” to a rival campaign at that time, but maintained that he would not know which campaign until an internal review is completed. He said that internal review could also result in further discipline for members of the Sanders campaign itself.

He also made assurances that none of the information gleaned from the Clinton breach had been used by the Sanders campaign and tried to deflect blame to Josh Uretsky, its national data director who was fired over the breach.

“In the heat of these campaigns, sometimes young people make misjudgments,” he said.

The Democratic Party has cut off Bernie Sanders' access to its massive voter database – a crucial tool presidential candidates rely on to target their operations – after it learned that Sanders campaign employees tapped into the private files of rival Hillary Clinton’s campaign.

The act of online campaign espionage, and the potential it has to hurt insurgent Sanders at a do-or-die moment in the campaign, underscores the ever-growing role data play in modern presidential campaigns, where resources are marshaled around precise formulas that factor in such details as where voters live, what magazines they read and even their latest purchases at big-box retailers.

Earlier in his campaign, Donald Trump predicted an agreeable relationship between himself and Russian President Vladimir Putin — and Putin responded somewhat in kind Thursday, calling Trump a “very colorful, talented person."

Trump responded with thanks and appreciation, and on MSNBC on Friday, he even defended Putin's sometimes lethal tactics.

"He’s a person that kills journalists and political opponents and invades countries," said "Morning Joe" host Joe Scarborough.

Trump’s response: At least Putin leads.

"Our country does plenty of killing also, Joe," Trump said. "You know, there’s a lot of stuff going on in the world right now, Joe. A lot of killing going on and a lot of stupidity."

Scarborough pressed Trump until he finally condemned some of Putin’s handling of journalists and opponents. But Trump continued to praise him for the way he leads Russia.

"I have always felt that Russia and the United States should be able to work well with each other towards defeating terrorism and restoring world peace," Trump said Thursday in response to Putin’s praise, "not to mention trade and all of the other benefits derived from mutual respect."

In the boxing match over immigration between Ted Cruz and Marco Rubio, Cruz earned a new supporter in his corner — conservative talk show host Rush Limbaugh. The Texas senator and Florida senator continued what Limbaugh called “muddled” attempts to pin soft-immigration stances on each other.

But for Limbaugh, Rubio’s involvement in the Gang of Eight senators who pushed immigration reform in 2013 damages his credibility.

“Ted Cruz never was and they’re trying to make it out like he was,” Limbaugh said. “At the end of the day, when people go vote, people are gonna remember, of the two, it was Marco Rubio that was a member of the Gang of Eight and Ted Cruz that wasn’t.”

Cruz and Rubio are battling to gain ground on businessman Donald Trump. Instead of attacking him together, they’ve started to target each other in an attempt to win the nomination. That has meant taking hard stances.

“Every time we listen to the voice of ‘run to the middle,’ we get ” Cruz said on Fox News this month.

He also detailed his immigration platform in the most recent debate after Rubio questioned it again. The Florida senator suggested his rival supports legalizing people already in the country illegally.

“Let’s have a moment of simple clarity: I oppose amnesty. I oppose citizenship. I oppose legalization,” Cruz said of immigration legislation.

Republican advisors and leaders view their attacks as a fight to outrun Trump, the GOP front-runner.

“Cruz and Rubio are now trying to throw elbows at each other because someone has to emerge as the only remaining candidate to take on Donald Trump,” said former press secretary for President George W. Bush Ari Fleischer.

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