In an interview with CBS, Vice President Joe Biden said Hillary Clinton "didn't understand the gravity" of her decision to use a private email server. Screenshot via YouTube

In an interview with CBS, Vice President Joe Biden said Hillary Clinton may have underestimated the "gravity" of her decision to use a private email server while she served as secretary of state.

“I don’t think she understood the gravity of setting it up. She thought this was okay to do,” Biden said.

"I think then when faced with this problem I think instead of just cutting and dealing with it immediately there's always an inclination of overthinking it,” he said.

Biden's comments were part of a taped interview set to air on CBS's "Face the Nation."

Hacked emails published by WikiLeaks reveals the Clinton campaign discussed the seriousness of the former secretary of state's use of a personal email account.

On Friday, FBI director James Comey released a vague letter announcing the agency was reviewing new emails related to the probe into Clinton’s private email server.

"The FBI cannot yet assess whether or not this material may be significant," Comey wrote in a letter. "I cannot predict how long it will take us to complete this additional work."

The FBI's announcement comes fewer than two weeks before Election Day.

In a last-minute press conference on Friday, Clinton urged the FBI to release information that it found because she was "confident" the new emails would not reveal any wrongdoing as a previous FBI investigation found.

“The American people deserve to get the full and complete facts immediately,” Clinton said.