U.S. officials said on Thursday that they are hopeful they will be able to unlock an iPhone used by one of the San Bernardino shooters without help from Apple Inc., but said the national debate over privacy and encryption must still be resolved.

Apple has been fighting a court order obtained last month requiring the tech giant to write new software and take other measures to disable passcode protection and allow access to the phone. U.S. prosecutors said on Monday that a third party had presented a possible method for opening the phone.

Attorney General Loretta Lynch told a news conference on Thursday that the Justice Department is "trying to exhaust all investigative tools" to gain information on the San Bernardino attackers, including by using techniques offered by third parties.