Democratic presidential candidate Hillary Clinton dismissed questions over her use of a private email server at the State Department as "nothing to worry about," saying Tuesday that the controversy was being fueled by Republicans who can't defeat her on the issues.

"This will burn itself out," Clinton said in an interview with Telemundo. "It's being turned into a partisan attack connected, unfortunately, with the continuing Republican partisanship over Benghazi, which was a great tragedy and has already been investigated from one side to the other."

The FBI is investigating the security of Clinton's personal server and the thumb drives that contain emails related to her work as secretary of state during President Barack Obama's first term.

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Clinton's campaign has previously acknowledged that there was an attempt to wipe the server before it was turned over last week to the FBI. But two sources with direct knowledge of the investigation told NBC News on Tuesday that the bureau may be able to recover at least some data.

"Look, I've been around a long time," Clinton told Telemundo News, a Spanish-language division of NBCUniversal. "I know when they can't beat you on the issues, when they can't beat you on your experience, ... they're going to come up with something, and you just have to keep smiling and go through it.

"There's nothing to worry about," she said.

Related: 305 Clinton Emails Flagged for Further Classification Review

A team of intelligence community reviewers also looking at emails from the server have identified 305 documents that have been referred to their agencies for further consultation, State Department lawyers said in a court filing Tuesday intended to update a federal judge on efforts to release the emails.

Clinton has said she used a private server to handle her State Department email for convenience. But at a campaign event Tuesday in Las Vegas, she conceded, "In retrospect, this didn't turn out to be convenient at all, and I regret that this has become a cause célèbre."

Clinton said conflicting reports about what may have been in her email or on the server reflected differing accounts by government agencies looking for different things.

"If it were a government account, they would be saying the same thing," she said. "Everybody's acting like this is the first time this has ever happened. It happens all the time."

The key takeaway, she insisted, is: "Whether it was a personal account or a government account, I did not send classified material, and I did not receive any material that was marked or designated classified."