Obama, who will travel to Denver this week, is set to accept the Democratic Party's nomination for president and speak at the stadium Thursday.
According to federal law enforcement, one of the suspects confessed to an ATF agent that the three men were looking for a high platform to take a shot to take a shot down at Invesco Field and kill Obama.
ABC sources said that with wind movement and distance, such a shot would not have had a chance of succeeding.
U.S. Attorney Troy Eid said in a statement that the matter is still under investigation, but that federal authorities are working "hand-in-glove" with the local authorities, namely the Aurora, Colo. Police Department.
"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," Eid added.
According to ABC sources, police stopped Tharin Robert Gartrell, 28, for erratic driving early Sunday morning. His rented Dodge Ram truck contained two bullet proof vests, wigs, ski masks, walkie-talkies a .270 Remington and a .22 Ruger rifle with scope.
Police said Monday that they believe one of the guns is stolen.
Authorities arrested two other men, 32-year-old Nathan Johnson and 33-year-old Shawn Robert Adolph after questioning Gartrell. All three men had tattoos of white supremacist imagery, authorities told ABC News.
All three suspects are now allegedly admitting to what federal sources described as a "crude plan." They are expected to face felony gun charges and probable drug charges.
The FBI is considering whether to charge the three with conspiracy to kill a presidential candidate.
