Joshua Uretsky, the Philadelphia man fired as data chief for presidential candidate Bernie Sanders after a controversial data breach involving Hillary Clinton's campaign, is an idealist and a progressive but not someone who would do something untoward to gain electoral advantage, friends and associates said Saturday.

They defended the 39-year-old Fishtown man against allegations that Uretsky and other Sanders staffers had tampered with the front-runner's confidential voter data Thursday after a security firewall temporarily vanished on the shared system the party and its candidates use to store voter data.

The allegation Friday was swiftly followed by the Sanders campaign suing the Democratic Party in federal court and also claiming no Clinton data had been misused.

The candidates seemed to put the issue to rest at a televised debate Saturday night where Sanders apologized to Clinton and his own supporters for the data breach, and said he would fire staffers if it happened again.

"This is not the type of campaign that we run," Sanders said in the opening moments of the third Democratic debate.

Clinton quickly accepted the apology from the independent senator from Vermont who is her closest rival in the Democratic race.

"We should move on because I don't think the American people are interested in this," she said.

As the bombast eased, Uretsky's handling of the breach, which the Sanders campaign said was caused by a vendor who administers the DNC system, remained a focus of scrutiny.

"He is not a schemer," said Adam Bonin, a Philadelphia election-law attorney and friend of Uretsky. "It's just impossible for me to imagine that he would be looking at this situation and say, 'Let's figure out how to exploit it for the campaign.'"

Reached Saturday at the rowhouse where he lives near Northern Liberties, Uretsky declined comment. Bonin said his friend was overwhelmed by the attention after initially offering explanatory interviews to national news outlets.

The Democratic National Committee on Saturday lifted its ban on Sanders from accessing its voter data.

The Sanders lawsuit had alleged the DNC ban was unwarranted, would badly hurt Sanders' fund-raising, and was evidence that the DNC was tilted to favor Clinton.

Tad Devine, senior adviser to the Sanders campaign, dismissed any notion that data had been tampered with or that the campaign had set out to exploit the accident.

Devine said Uretsky had mishandled things by not immediately reporting to top staffers that a system problem had caused Clinton voter information to appear in Sanders' computers Thursday. That's why he was fired that day, before it became public, he said.

Uretsky's lack of experience on major campaigns - his highest previous post was crunching data for a progressive coalition of labor unions and other groups in Pennsylvania - "certainly could contribute to this," Devine said.

Devine said Uretsky and three data team members spent around a half hour poking around in the system after realizing a data breach had occurred.

They probed in an effort to determine if their data, also, had been rendered vulnerable, Devine said.

"I believe that I took appropriate steps to audit and assess the security breach and that nothing I did was done in a way that it would give the Sanders campaign a competitive advantage," Uretsky told The Associated Press.

The real problem, from the Sanders camp's perspective, was that Uretsky did not immediately tell a supervisor, Devine said. An elections veteran working on a different Sanders data crunch in October also detected a data breach but immediately reported that to top officials, Devine said.

After being fired, Uretsky suddenly found himself in the spotlight.

"It's just such an unusual position to be in, to go from your job one day, to all of a sudden you've got national reporters calling, trying to get you to go on TV," said his friend, Bonin.

Uretsky's friends in progressive Philadelphia circles doubt he would behave unscrupulously.

"He's dedicated his life to trying to implement things that he believes in," said Dan Fee, a longtime political consultant who runs The Echo Group in Philadelphia.

Fee got to know Uretsky when Fee was managing the successful 2009 campaign for Philadelphia District Attorney Seth Williams, a Democrat. Uretsky was a field worker in that race, Fee said.

He called Uretsky a man of "integrity."

He was not alone in saying that.

"I have trusted Josh with data for a long time," said Kati Sipp, director of Pennsylvania Working Families, an independent political organization that champions progressive causes.

Sipp said she worked with Uretsky on voter targeting efforts on various races over the past six years, including while Uretsky was on staff at America Votes Pennsylvania. One such campaign included the successful primary bid earlier this year by Philadelphia Mayor-Elect Jim Kenney.

America Votes is an umbrella group that does work on behalf of collective labor union members and other like-minded Democratic groups. Uretsky was Pennsylvania data and targeting manager for America Votes from November 2011 until September, when he left to join Sanders, according to his LinkedIn profile.

Before that, from Aug. 2007 to Nov. 2008, he was cochair of Philadelphia for Obama, a grassroots group that formed separate from the Obama campaign apparatus to help elect the nation's first African American president.

The DNC said it would continue to investigate to ensure the Sanders campaign no longer had Clinton voter data in its possession.

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