This, after there were 4 arrests on Sunday after hours of tense standoff between police and hundreds of demonstrators, many of them spouting the rhetoric of anarchists.
"You think you're defending freedom? It's so obvious what you're doing!" one protestor shouted. "It's so obvious!"
Street demonstrators are in Denver to make their voices heard on a number of issues.
Security is so beefed up this week that 900 extra cops are on the street…hundreds are inside the city from surrounding towns.
"I wouldn't say we're tense. We' ready," said Sgt. Marc Direzza of the Lakewood, Colorado police. "We've done a lot of training to get to this point."
Police are armed with nearly 100 new pepper guns, handy for dispering a hostile crowd if things boil over.
Security officials have 2 big venues to watch over this year. The Pepsi Center where the convention will be held for the first three days, and Invesco Field, the 76-thousand seat open-air stadium where Barack Obama will deliver his acceptance speech before a sell-out crowd.
The Secret Service is emphasizing that there are no known direct terrorist threats to the convention.