The State Department agreed Thursday to review thousands of emails from a private account that Hillary Rodham Clinton used for government business as secretary of state, but warned that the process could take months to complete.
Secretary of State John F. Kerry said the department “will undertake this task as rapidly as possible in order to make sure that we are dealing with the sheer volume in a responsible way.”
But other State Department officials said the review of about 55,000 pages of emails will last several months, meaning it could further complicate Mrs. Clinton’s anticipated presidential campaign announcement this spring or summer.
Mrs. Clinton broke her silence on the burgeoning controversy shortly before midnight Wednesday by posting a note on her private Twitter account.
“I want the public to see my email,” she wrote. “I asked State to release them. They said they will review them for release as soon as possible.”
A spokesman for the House Select Committee on Benghazi, which has issued a subpoena for Mrs. Clinton’s emails, said the panel rejects her explanation.
“The former Secretary’s tweet does not answer questions about why this was not done when she left office, the integrity of the emails while she controlled them, the scheme to conceal them, or the failure to provide them in logical course,” said committee spokesman Jamal Ware.
Satisfactory or not, the tweet was Mrs. Clinton’s first comment on the matter since it was reported Monday that she used the private email account exclusively for State Department business and never used a government email account as recommended by administration officials, ethicists and cybersecurity specialists.
Federal law allows government employees to conduct official business on personal email accounts, but they are now required to forward such correspondence to their government email accounts within 20 days to preserve the records.
Speaking in Saudi Arabia, Mr. Kerry said the department “has had access to a wide array of Secretary Clinton’s records, including emails, between her and department officials with the State.gov accounts, as well as cables, as they do for every secretary of state.”
He wasn’t sure whether the department was in possession of all of his predecessor’s correspondence from her “Clintonemail.com” account.
While some Democrats worried about the content of the emails and the potential impact on the presidential race, other party leaders predicted that the issue wouldn’t hurt Mrs. Clinton’s candidacy.
Former Pennsylvania Gov. Edward G. Rendell, a longtime ally of Mrs. Clinton and a former Democratic National Committee chairman, said Democrats with whom he had spoken weren’t concerned about the revelations.
“It’s no big deal,” Mr. Rendell said in an interview. “It’s only a big deal because she remains Hillary Clinton.”
Mr. Rendell noted that Jeb Bush, a likely candidate for the Republican presidential nomination, used the personal email account “email@example.com” to conduct some of his official business as Florida governor. Mr. Bush also owns the server that runs the account.
South Carolina Democratic Party Chairman Jaime Harrison said he is “not reading concern from Democrats” about the issue.
“I just don’t think there’s any ‘there’ there,” Mr. Harrison said.
The Republican National Committee accused Mrs. Clinton of engaging in “tried and true” evasion tactics that it said were typical of her and former President Bill Clinton.
“Hide the candidate, baselessly claim that reports are false, and release a series of talking points detached from reality,” said RNC spokesman Raj Shah.
As the political firestorm raged, there were accusations that Mrs. Clinton employed a double standard on State Department communications by using a private email system for herself while others were disciplined for the same thing.
Foreign Policy magazine reported that U.S. Ambassador to Kenya Scott Gration stepped down in 2012 after a harsh evaluation from the State Department, including criticism that he had set up a private email system.
“During the inspection, the ambassador continued to use commercial email for official government business,” the report said. “The department email system provides automatic security, record-keeping, and backup functions as required. The ambassador’s requirements for use of commercial email in the office and his flouting of direct instructions to adhere to department policy have placed the information management staff in a conundrum: balancing the desire to be responsive to their mission leader and the need to adhere to department regulations and government information security standards.”
It was not immediately clear what procedure or protocols the State Department was using to review Mrs. Clinton’s emails, or what U.S. laws or rules might prohibit her from releasing her own emails immediately.
Mrs. Clinton’s spokesman and the State Department have said she never received or transmitted classified information on the private email account, so there should be no such concerns that disclosure of her messages could compromise national security.
“She had other ways of communicating through classified email through her assistants or her staff, with people, when she needed to use a classified setting,” State Department spokeswoman Marie Harf said.
Under the Freedom of Information Act, the government can censor or withhold emails and other records under nine categories intended to protect information that would hurt national security, violate personal privacy or expose business secrets or confidential decision-making in certain areas.
It wasn’t clear whether the State Department would automatically apply those provisions to its review of Mrs. Clinton’s emails or whether it would invoke its legally authorized discretion to release even emails that might be covered under those exemptions.
Under the open records law, withholding emails merely because they might be embarrassing or expose government incompetence or malfeasance is not permitted.
“I understand the State Department will now redact personal phone numbers and other information, which may take some time, but I believe this decision is the right one,” said Rep. Elijah E. Cummings of Maryland, the senior Democrat on the House Select Committee on Benghazi.
It also wasn’t clear what resources the State Department intended to use to review Mrs. Clinton’s emails or how long the process would take. The agency has 127 employees who review emails requested under the federal open records law, but they are overwhelmed with nearly 11,000 other pending requests, which for complex cases can take more than 18 months to review.
• This article is based in part on wire service reports.