GOLDEN, Colo. -- President Obama continued his march through the suburban battlegrounds of the United States on Thursday with an appearance before a crowd of 8,400 in this mountain-ringed community near Denver.

Obama again made the case that he is looking out more for the middle class than his Republican opponent Mitt Romney. He portrayed himself as the pragmatic, non-ideological choice in this election — a clear appeal to the unaffiliated voters who have moved into the Denver suburbs in droves in recent years.

As he did in Las Vegas the previous evening, Obama opened his remarks with a reference to the violence in Libya this week that claimed the lives of four Americans, including U.S. ambassador to Libya J. Christopher Stevens. Balancing the need for sobriety with the red-meat demands of an exuberant crowd that repeatedly broke into cheers of “four more years,” Obama paid tribute to the lives lost, but also promised to avenge their deaths by finding their killers.

“I want people around the world to hear me,” Obama said. “To all those who would do us harm: No act of terror will go unpunished. It will not dim the light of the values we proudly present to the world.”