Johnson was arrested by FBI agents in October after an investigation identified him as the caller who left more than a dozen threatening and profanity-laced voicemails for both senators.
The 65-year-old Johnson was arrested Oct. 4 and since then has been held at Fairbanks Correction Center.
FBI agents arrested Johnson on Oct. 4 on suspicion of leaving 17 threatening voicemail messages for Sens. Lisa Murkowski and Dan Sullivan earlier this year.
A federal judge ruled Friday that a Delta Junction man accused of threatening to kill one of Alaska’s two U.S. senators must remain behind bars until an Oct. 19 preliminary hearing.