Oath Keepers founder Stewart Rhodes and members of his anti-government group will be the first Jan. 6 defendants sentenced for seditious conspiracy.
A series of hearings beginning this week will set the standard for more punishments of far-right extremists to follow.
Prosecutors will urge the judge on Thursday to put Rhodes behind bars for 25 years, which would be the harshest sentence by far handed down in the U.S. Capitol attack.
The Justice Department says stiff punishments are crucial to sending a message to future possible instigators of political violence.
The hearings will begin Wednesday when prosecutors and defense lawyers are expected to argue over legal issues concerning sentencing and begin hearing victim impact statements.
Rhodes, from Granbury, Texas, and Florida chapter leader Kelly Meggs — who was convicted of seditious conspiracy in November — will receive their sentences Thursday, and six more Oath Keepers will be sentenced later this week and next.