The FBI’s probe into the security of Hillary Rodham Clinton’s e-mail has expanded to include a second private technology company, which said Tuesday it plans to provide the law enforcement agency with data it preserved from Clinton’s account.

The additional data, provided by Connecticut-based Datto Inc., could open a new avenue for investigators interested in recovering e-mails deleted by the former secretary of state — now the Democratic presidential front-runner — that have caught the interest of GOP lawmakers.

Datto’s work on the Clinton e-mail system became public Tuesday when the Republican chairman of the Senate Homeland Security Committee sent the company a lengthy letter seeking information about the role it and other firms played in managing the Clinton e-mail system.

Datto was hired to provide backups for the Clinton e-mail accounts starting in May 2013 by Platte River Networks, the Colorado-based tech firm hired earlier that year by the Clinton family to manage the system after Hillary Clinton concluded her term as secretary.

The FBI has been investigating whether classified information may have been improperly stored and transmitted through Clinton’s private server.

During an interview with ABC News, Hillary Clinton apologized for using a private e-mail server during her time as secretary or state. Here are past statements where the presidential hopeful neglected to take personal responsibility for the controversy. (The Washington Post)

Platte River handed over a server to the FBI in August.

An official from Datto told The Washington Post on Tuesday about his company’s interactions with the federal investigators.

“Datto is working with the FBI to provide data in conjunction with its investigation,” said Michael Fass, general counsel at Datto.

Fass said Datto had received consent to turn over data from the Clintons and from Platte River. A Datto official said the FBI would receive a “node,” a piece of hardware the company housed in Pennsylvania that allowed it to store data on its cloud.

Brian Fallon, a spokesman for the Clinton campaign, accused Senate Homeland Security Committee Chairman Ron Johnson of “ripping a page from the House Benghazi Committee’s playbook and mounting his own, taxpayer-funded sham of an investigation with the sole purpose of attacking Hillary Clinton politically.”

“The Justice Department is already conducting a review concerning the security of her server equipment, and is fully aware of Datto’s role in providing services to Platte River Networks. The Justice Department’s independent review is led by nonpolitical, career professionals, and Ron Johnson has no business interfering with it for his own partisan ends,” he said in a statement.

A spokesmen for the FBI did not respond late Tuesday to requests for comment. Peter Carr, a spokesman for the Department of Justice, declined to comment.

Catch up on the controversy and read the emails

It is not clear whether the data provided by Datto includes any material from Clinton’s time as secretary of state. Late Tuesday, officials from the two tech firms disagreed about the possibility that years-old e-mails Clinton has deemed personal and deleted could be recovered by the FBI.

A Datto official said that investigators may be able to recover the e-mails if the data existed at the time the company was hired in May 2013 and had not been altered since.

A spokesman for Platte River, Andy Boian, said his company assumed that Datto would have retained data for only a short period and older e-mails would no longer be available.

The role of an additional private firm in maintaining Clinton’s e-mail adds yet another wrinkle in an unfolding controversy that has emerged as an issue for Clinton’s White House bid.

Clinton has turned over thousands of pages of e-mails to the State Department for public release, but some Republican lawmakers have called for the 31,000 deleted e-mails she deemed personal to be recovered. The GOP lawmakers have questioned whether they contained classified or otherwise sensitive national security information.

The letter to Datto from Sen. Ron Johnson (R-Wis.) cited e-mails and other documents that have been turned over to the committee by Platte River in recent weeks that show a more complicated array of companies involved in managing the Clinton e-mail system than had previously been publicly known.

The letter, in requesting additional information, describes a Clinton family entity called Clinton Executive Service, which contracted with Platte River after Hillary Clinton left the State Department.

Of particular interest to Johnson, according to his letter, is whether Datto was authorized to store classified information and whether the firm has come under cyberattack.

The letter cites some colorful internal e-mails from Platte River that were sent in August as the company’s role in the controversy gained widespread attention.

In one exchange, a Platte River employee working on the Clinton account discusses with a colleague whether there was a written record of a “directive to cut the backup.”

The context is not clear, but it suggests there was growing anxiety over how the system was managed and who would be held responsible. At about the time of that exchange, Platte River had been in discussions with Datto about the length of time Clinton e-mail data was preserved and whether copies were saved, according to a person familiar with the discussions.

“If we had that email we are golden,” the employee wrote.

“Starting to think this whole thing really is covering up some shaddy [sic] shit,” the employee wrote.

Boian, the Platte River spokesman, said he had no idea what the coverup conversation referred to, but he said, “I can tell you emphatically that Platte River Networks does not believe that any cover up has occurred.”

Spencer S. Hsu contributed to this report.