MORRISON, Colo. (AP) – Republican presidential candidate Mitt Romney on Tuesday rallied thousands of supporters at the majestic Red Rocks Amphitheatre, casting his bid as a candidacy on the upswing and saying Democratic President Barack Obama’s bid is waning.

Obama’s promise of more of the same “is why he’s slipping and it’s why we’re gaining,” Romney told the cheering crowd of over 10,000 gathered in the open-air amphitheater cut into mountain rocks outside Denver.

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Romney is working to project optimism, though polls show a close race in the final two weeks of the campaign.

“We’re in the home stretch now, and I think the people of Colorado are going to get us all the way there,” Romney said, looking out at a crowd that had been given colored t-shirts so they formed the shape of the Colorado state flag when viewed from afar.

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At the amphitheater, known for hosting live music, rocks rose on either side of the crowd. The campaign lit them with blue lights and the Romney “R” logo.

It was one of Romney’s largest events to date. He’s typically held campaign rallies at local small businesses, in town squares or even, in one instance, in a back parking lot of a wheelchair company. That was largely aimed at holding down costs.

With the election just two weeks away, though, the events are getting bigger – and more expensive. Red Rocks costs around $100,000 to rent for an evening.

The audience at Red Rocks (credit: CBS)

As he walked to the microphone, Romney put his hand over his heart, thanked the crowd and marveled at the setting.

“You look at the handiwork of our creator,” he said. “It’s just overwhelming.”

The amphitheater, though, is partly man made. Workers with the Works Progress Administration and other government agencies spent years building it into a public venue as part of President Franklin D. Roosevelt’s New Deal.

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The Red Rocks event came after a rally in Henderson, Nev., at another open-air amphitheater. Romney had the same message there, calling Obama the “status quo” president.

“We haven’t heard an agenda from the president and that’s why his campaign is taking on water and our campaign is full speed ahead,” Romney said there.

He accused Obama of running a small campaign.

“He’s been reduced to try to defend characters on ‘Sesame Street’ and … word games of various kinds, and then misfired attacks after one another. You know the truth is that attacks on me are not an agenda,” Romney said.

Kid Rock performing at the Romney event at Red Rocks (credit: CBS)

The pair of events were the beginning of an aggressive multistate swing that represents a significant uptick in the pace of campaigning. Through the end of the week, Romney had a packed schedule planned in the states most critical to his bid. He was set to fly back to Nevada for an event in Reno on Wednesday before touching down briefly in Cedar Rapids, Iowa.

Then he planned to overnight in Cincinnati ahead of a three-stop campaign swing in Ohio on Thursday. On Friday, he’ll stop in Ames, Iowa, before turning right back around to spend the night in Akron, Ohio.

On Saturday, he’ll be in Pensacola, Fla.

Romney’s advisers have been particularly optimistic in recent days as polls have shown a close race in the critical battleground states. Aides say their internal data shows them even in Ohio, where Romney will spend three nights this week. With 18 electoral votes, it’s critical to their hopes.

The schedule shows an intense effort to shore up Romney’s support even in places where Obama seems to have advantages – Iowa and Nevada, for example – states that could make a difference in a close Electoral College contest.

– By KASIE HUNT, Associated Press

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