Authorities said Gartrell was pulled over in the Denver suburb of Aurora in a rented truck that contained rifles, a bulletproof vest, wigs and fake IDs, and that Gartrell, two other men and two women had talked about killing Obama.
In one conversation, the FBI affidavit refers to "shooting on a grassy knoll," a reference to the assassination of President John F. Kennedy in Dallas.
Gartrell was ordered held without bond until a federal court hearing next week. The charges against him on drug and weapons violations were to have been heard in state court Thursday but was transferred to federal court.
During his appearance in front of a federal magistrate Thursday afternoon in Denver, Gartrell was handcuffed to a pair of crutches. He was also on crutches when arrested last weekend. Witnesses reported that he spoke little and did not enter a plea.
Public defender Ed Harris was appointed to represent him.
U.S. attorney's spokesman Jeff Dorschner said it was "best from a coordination standpoint" if the cases against Gartrell and the two other men were in federal court. Such a transfer is not unusual if state prosecutors agree that a suspect could received a harsher sentence in federal court.
Despite the weapons, ammo and discussions of various schemes to kill Sen. Obama, federal authorities have said they don't consider that the Democratic presidential nominee was in any danger.
The two other men arrested in the case are Shawn Adolf and Nathan Johnson. Both face federal firearms and drug charges. Dorschner said neither is expected to appear in court this week.
The two women who participated in the meth sessions and the talk of assassinating Obama have not been named by authorities or charged with any crime.