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.

Those suburbs, particularly Arapahoe and Jefferson counties (the latter home to Golden), are widely expected to decide the presidential election in Colorado — and perhaps nationally. As in other battleground states such as Virginia and North Carolina, these populations of moderate, independent-minded voters help explain Obama’s emphasis on such issues as keeping health-care costs down, investing in renewable energy, keeping taxes down for the middle class (but not lowering them for the wealthy) and protecting college aid.

Obama turned to a newer riff, poking fun at Republicans for holding up tax cuts as the answer to all woes.

“You need to make a restaurant reservation, you don’t need a new iPhone,” Obama said. “There’s a tax cut for that,” he said.

(In Las Vegas on Wednesday, Obama had said that the GOP turns to tax cuts even to “give your love life that extra kick.”)

As he had also done 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.”

As in Las Vegas, Obama did not mention Romney by name when he pivoted back from Libya to his stump speech.

Obama also noted that he is the first sitting president since Ulysses S. Grant to visit Golden, a picturesque former mining town and longtime headquarters of Coors Brewing where statues of cowboys mix with coffee shops and wine bars. Obama spoke in an outdoor park which, though squishy and soggy from two days of badly needed torrential rain, was bathed in sunshine and blue sky for the president’s visit.

It is hardly Obama’s first trip to Colorado, however: Thursday represented his ninth trip to the state this year, with several of his previous visits taking him to college campuses to gin up support among crucial younger voters.