The State Department has told a federal court that processing a Republican National Committee demand for documents relating to Hillary Clinton and her aides would take as long as 75 years – and would stretch “generations.”

The department made the argument in a bid to fight the request, just one of several legal battles still unfolding over the former secretary of state’s personal email use.

The RNC had sued the department back in March for the records. The party is seeking years’ worth of emails for top Clinton aides including former chief of staff Cheryl Mills, adviser Jacob Sullivan and Bryan Pagliano, an IT specialist who helped set up Clinton’s server and struck an immunity deal with the Justice Department in the ongoing FBI probe.

A court filing last Wednesday before the U.S. District Court for the District of Columbia estimated that -- not counting the Pagliano request – processing the records would take 75 years, considering the time it takes to review what would be hundreds of thousands of pages.

“FOIA requests are not supposed to be labored over for generations,” said the court filing, which sought summary judgment on the basis the RNC request was too broad and burdensome.  

State Department officials defended the court filing on Tuesday.

Spokesman Mark Toner told Fox News the claim it could take 75 years is “not an outlandish estimation, believe it or not.”

Meanwhile, Pagliano also moved Tuesday to keep his own records under wraps in a separate case.

The ex-staffer who set up Clinton's home email server filed documents under seal in response to a judge's directive that he reveal his immunity arrangement with the Justice Department.

The motion was hidden from public view, and two exhibits were also sealed.

Pagliano last week said he would not testify in an upcoming deposition sought by conservative legal advocacy group Judicial Watch, which has sued for information about Clinton's email server.

In response, U.S. District Judge Emmet Sullivan gave Pagliano until Tuesday evening to file with the court a copy of his immunity agreement.

On another front, the State Department said Tuesday that Clinton’s use of private email was not widely known, further undercutting claims she made as recently as Sunday.

Speaking with ABC News, Clinton said, “Everybody in the department knew that I was emailing from a personal address. Hundreds of people knew it.”

Toner, though, said Tuesday that “really no one among the senior staff had a full and comprehensive knowledge of how much she was using her personal email and if they had, they probably would have done it differently.”

The State Department was responding to questions about the deposition of aide Stephen Mull in a civil lawsuit. Mull, who ran Clinton's office, said he couldn't remember when he first learned about her private email, or why he suggested she get a government email account instead.

Fox News’ Catherine Herridge and The Associated Press contributed to this report.