LIVE from Denver: Assassination plot?

Apologists for the Mile High security we've got here in Denver will probably argue that this incident - which we still don't know very much about - justifies all the militarization around the PepsiCenter:

Authorities are investigating a possible threat against presumptive Democratic presidential nominee Barack Obama.

Aurora police arrested a longtime drug user Sunday afternoon during a routine traffic stop where the man was seen "weaving," sources said. Two possible other accomplices also were arrested, according to police.

Police found four weapons, including two rifles and two handguns, in a rented pickup.

That arrest then led authorities to a second man staying at the Cherry Creek Hotel at 600 South Colorado Blvd in Glendale. When authorities knocked on the man's door, they say he jumped out of his sixth floor window, landing on an awning and running from the scene. They say they soon found him with a broken ankle. He too was arrested.

The local news got the assassination story going with this report:

CBS4 had reported one of the suspects told authorities that they were "going to shoot Obama from a high vantage point using a ... rifle … sighted at 750 yards."

Law-enforcement sources told CBS4 that one of the suspects "was directly asked if they had come to Denver to kill Obama. He responded in the affirmative."

The U.S. Attorney for Colorado, however, says that the feds are confident Barack Obama isn't threatened. A news conference has been scheduled for this afternoon to brief the press on the matter.