Colorado is one of several states nationwide where a few motorcycle clubs engage in drug running with some members adopting White supremacist or neonazi ideology. The regions where this is more common include the Rocky Mountain States, the Western Midwest, the Pacific Coast, the Southeast, and New England.
Turf-related murders or revenge killings do occur within such groups, however...
...since this is primarily an illegal commercial enterprise, rather than an ideological mission, it would be very unusual for participants in such a criminal network to want to call attention to themselves by carrying out the political assassination of a major public figure such as Barack Obama.
In barroom bluster or heated arguments within such subcultures, hyperbolic threats would be a common occurrence, but seldom resulting in actual acts of violence. Police informer reporting of such threats needs to be investigated, but placed in the proper context.