LAKEWOOD, Colo. — In his second solo campaign event as the presumptive GOP vice presidential nominee, Rep. Paul Ryan (R-Wis.) on Tuesday morning delivered a sharp critique of President Obama’s energy policy, arguing that the president “has done all that he can to make it harder for us to use our own energy.”

Republican vice presidential candidate, Rep. Paul Ryan (R-Wis.) waves to supporters as he enters during a campaign rally in Lakewood, Colo., Tuesday, Aug. 14, 2012. (Jack Dempsey/Associated Press)

Before a mostly older crowd of around 3,000 people at Lakewood High School, Ryan spoke of the country’s energy policy in broad terms, contending that through over-regulation and a refusal to tap domestic resources, there has been a “failure of leadership” under Obama.

But there was no mention by Ryan of his signature plan to overhaul Medicare — a proposal that has been a rallying point for the conservative base and which has become a flashpoint in the presidential campaign in the days since Romney tapped Ryan.

“Here is our promise to you: We are not going to duck the tough issues. We are going to lead,” Ryan told the crowd to boisterous cheers.

The event came as Romney’s campaign is gearing up to release a new TV ad taking aim at Obama for the $716 billion in savings in Medicare provider payments expected over the next decade through the national health-care law.

“The message here is that we are on offense on Medicare. ... This a debate we invite,” said the aide, who spoke anonymously in order to discuss campaign strategy.

Ryan is also expected to address the issue in an interview with Fox News Channel’s Bret Baier, which was taped Monday and will air Tuesday night at 6 p.m. Eastern.

Asked why Ryan made no mention of Medicare at Tuesday’s Colorado event, the aide responded: “Today’s event was about energy.”

And asked about Democrats’ argument that the more than $700 billion in Medicare savings would be geared toward providers and not to beneficiaries, the aide said: “That is a distinction without a difference.”

In his 20-minute remarks, Ryan charged that Obama’s policies have been “demonizing small business” and said that if he and Romney are elected, the two will seek to roll back regulations and will approve the Keystone XL oil sands pipeline.

The crowd gave Ryan a raucous welcome, and at one point attendees stomped their feet on the bleachers in the Lakewood High School gymnasium as Ryan was being introduced. His biggest applause line came not on energy policy, however, but rather when he told the crowd: “We also have to stop spending money we don’t have.”

Since being tapped as Romney’s running mate, Ryan has sought to balance his dual roles of partisan attack dog and GOP ideas man, and both sides were on display at Tuesday’s event.

In his role as the former, he told the crowd that “we’ve gone from hope and change to attack and blame.”

“This is the worst economic recovery — if you can call it that — in 70 years,” he said.

Picking up on the GOP theme that Obama is waging “class warfare,” Ryan charged that Obama is “speaking to people as if we’re stuck in our station in life, victims of circumstances beyond our control, and that only the government is here to help us cope with it.”

“You know, I don’t know about you, but when I was growing up, you know, when I was flipping burgers in McDonald’s, when I was ... washing dishes or waiting tables, I never thought of myself as stuck in some station in life,” he said.

And he argued that Romney “is living proof of the example that if you have a small business, you did build that small business.”

In an appeal to voters in this key swing state, Ryan also told the crowd of how he and his family have frequently vacationed in Colorado — and noted that his wife and children are camping in the state this week.

“There’s nothing like the stars and the skies and the Colorado Rockies at night,” he said. “It is something else. We look at our kids, and we know that they are our future. But today, we look at our kids, and we know without a shadow of a doubt that we are mortgaging their future. ... We are giving them a diminished future, and President Obama has made it worse.”

While the crowd at the event was mostly older, Ryan was introduced by the student body president of Lakewood High School.

And his conversational approach on the stump — he roamed the stage using only a handheld microphone — appeared to have won over a few fans in the crowd.

“Look, no teleprompter!” one man in the crowd yelled, to applause from the rest of the audience.