Nathan Johnson, 32, an associate of Gartrell and Adolph, was also arrested Sunday morning. He told authorities that the two men had "planned to kill Barack Obama at his acceptance speech."

"He don't belong in political office. Blacks don't belong in political office. He ought to be shot," Johnson told Maass.

"Do you think they were really plotting to kill Obama?" Maass asked.

"I don't want to say yes. I don't want to say no," he said.

"We're aware of the matter discussed tonight by the Aurora Police Department," said Colorado U.S. Attorney Troy Eid in a statement late Monday night. "Federal law enforcement is working hand-in-glove with the Aurora Police Department. Because this matter is currently under investigation, there is little we can say right now.

"We can say this: We're absolutely confident there is no credible threat to the candidate, the Democratic National Convention, or the people of Colorado."

Law enforcement sources told Maass that one of the suspects "was directly asked if they had come to Denver to kill Obama. He responded in the affirmative."

Law enforcement sources say [Shawn Robert] Adolph broke an ankle in the fall and was captured moments later. Sources say he had a handcuff ring and was wearing a swastika, and is thought to have ties to white supremacist organizations.

Maass reported earlier Monday that one of the suspects told authorities they were "going to shoot Obama from a high vantage point using a ... rifle ... sighted at 750 yards."