The U.S. Senate is holding a confirmation hearing for President Barack Obama's pick to become the next Federal Bureau of Investigation director, James Comey.
The FBI Agents Association has told committee chairman Patrick Leahy it supports Comey's nomination.
Leahy, a Democrat from the northeastern state of Vermont, said at the hearing opening Tuesday he hopes Comey would lead an FBI that protects whistleblowers who reveal misconduct in the government.
Comey told the Senate that retaliation against whistleblowers is "unacceptable."
The FBI is investigating former U.S. intelligence contractor Edward Snowden, who leaked secret details of surveillance programs conducted by the U.S. National Security Agency.
The NSA says the information it has collected helped foil terrorist attacks. Snowden has said Americans should know their government has them under surveillance.