A congressional committee issued subpoenas Wednesday seeking information about Hillary Rodham Clinton's use of a private email account for official business while she was secretary of state, setting up a potential legal clash with the presumptive Democratic front-runner for president.

The move followed the revelation that Clinton had installed a private server at her New York home that allowed her, and not the State Department, to store her email correspondence and later decide which ones to turn over as public records.

The subpoenas, sent by the special House committee probing the fatal 2012 terrorist attack on a U.S. diplomatic compound in Benghazi, Libya, reflected the angry response more broadly from Republican lawmakers and conservative watchdogs who said Clinton's private email system allowed her to evade scrutiny from investigations and legal proceedings.

Meanwhile, government transparency advocates expressed concern over the level of control Clinton had asserted over her records. Security experts wondered if hackers could exploit weaknesses in the Clinton server to gain access to sensitive information.

And, on the political front, some Democrats worried about whether the email issue would damage Clinton's strength as a presidential candidate.

"There's always another shoe to drop with Hillary," said Dick Harpootlian, a former Democratic Party chairman in South Carolina who has said he hopes Vice President Joe Biden runs. "Do we nominate her not knowing what's in those emails?"

The subpoenas issued Wednesday seek all Clinton emails related to Libya during her time as secretary of state -- an attempt to collect new emails sent from the clintonemail.com domain, the private account Clinton established when she took office in 2009.

Also Wednesday, the president of Judicial Watch, a conservative watchdog group, said the organization is considering filing legal petitions to reopen as many as nine cases in which the group unsuccessfully sought public records from the State Department. The cases were either dismissed, closed or settled after the administration claimed it found no records involving Clinton related to the group's requests.

And other lawmakers who have tried to investigate Clinton's tenure at State said they were outraged and felt misled, and were concerned many of the public records they had requested had not been provided because of the use of private email.

State Department officials have confirmed that Clinton exclusively used a personal account, instead of a government email address, during her time in office.

Instead of using State Department servers to send and receive those emails, she used a server housed at her private home in Chappaqua, New York, a Clinton ally familiar with her email practices confirmed Wednesday. The server's existence was first reported by The Associated Press.

The Clinton ally said the server and email addresses were established following the conclusion of Clinton's unsuccessful bid for president in 2008, as she was transitioning away from using an account held by her defunct campaign.

Neither State Department officials nor Clinton aides would provide information about which officials had signed off on the arrangement, whether a legal analysis was performed and whether any agency officials ever raised questions about Clinton's email system.

Clinton herself has said nothing about the email issue, and her spokesman has not expanded on a brief statement issued Monday, in which he said Clinton had complied with both the letter and spirit of the law. The spokesman, Nick Merrill, also said that other secretaries of state have used private email accounts.

State Department officials said Clinton turned over 55,000 pages of email records last year after officials requested that former secretaries turn over public documents in their possession.

But, agency officials said, the decision over which emails would be deemed public record fell to Clinton and her private advisers -- not to government officials or archivists.

State Department spokesman Marie Harf told reporters Wednesday that she could not answer "when it was set up, and all that." She referred questions about the system's security to Clinton's personal office.

Harf said there was no indication that Clinton had used the account for classified information, but she acknowledged that she was relying on information conveyed by Clinton and her aides.

White House spokesman Josh Earnest also defended Clinton, saying he had seen no evidence to suggest Clinton's team had failed to turn over everything in its possession. But Earnest also took pains to say that he was relying on the Clinton team for his information.

"I also want to just be crystal clear about the fact that this is a responsibility that they assumed," he said.

Federal regulations in place while Clinton was in office required that emails sent on non-government accounts be preserved in the "appropriate agency record-keeping system." Harf said the regulation contained no "time requirement" to turn over records, meaning Clinton's response -- more than a year after she left office -- complied.

But government transparency advocates said the use of a private email account and a private server meant that for years, Clinton's emails were off-limits to public records requests filed with the state department.

The long delay in turning records over to the State Department also places enormous power in the hands of her closest aides to decide which of her emails should be made public and which should be shielded from view.

"There's no legitimate way to claim that there wasn't a requirement, certainly to keep with the spirit of the law, to make real-time copies available to the agency," said David Sobel, senior counsel for the Electronic Frontier Foundation.

In Congress, Rep. Jason Chaffetz , R-Utah, chairman of the House Oversight and Government Reform Committee, said new subpoenas were a good step because lawmakers do not have confidence Clinton has turned over all of her relevant emails to the State Department.

Agency officials have said they have submitted 300 of Clinton's emails to the committee investigating the Benghazi attack.

"The prime reason to set up an account like this is to skirt the law, avoid disclosure," Chaffetz said. " The question isn't the number of emails she has turned over, it's the percentage. I want to know who decided what we could see."

Likewise, U.S. Sen. Charles Grassley, R-Iowa, said he is concerned that the State Department did not turn over all emails by Clinton aide Huma Abedin that he requested in 2o13, as part of an effort to see whether Abedin was simultaneously working for the government and an outside consulting firm.

Abedin, like Clinton, sometimes used a private clintonemail.com account.

"The trend of using private email for public business is detrimental to good government," Grassley said. "The public's business ought to be public with few exceptions."

A number of Democrats insisted Wednesday that the email issue would fade quickly in voter's minds.

"As somebody who desperately wants her to run and wants her to win, on a scale of 1 to 10 this is a negative 12," said Paul Begala, a longtime Clinton family friend and Democratic strategist. No real voter, Begala said, is going to base a decision on whether "she had a non-archival-compliant email server."