An analysis this fall by Lang and others identified Arapahoe as the top swing county in the Centennial State, its neat subdivisions home to college-educated suburbanites who have tended to vote Republican in the past but are divided this year.
Coupled with Colorado's growing ranks of Hispanic voters, they have given Obama an average lead of 6 percentage points in the four public statewide surveys taken over the past week.
Californians move in
Dale Lanham, for one, dismisses the polls.
"I think that the true leaning of Colorado is still Republican," he says, noting he doesn't trust news coverage of the election. Lanham, 62, a Navy veteran and retired telecommunications technician from Littleton, brought his golden retriever, Roxie, to an appearance by Todd Palin, the husband of GOP vice presidential nominee Sarah Palin.
Roxie sports an American flag scarf around her neck and a red-white-and-blue T-shirt across her back that reads, "We don't surrender to terrorists."
"Obama wants to legislate defeat when we've already won the war (in Iraq), and his taxing agenda is socialistic," Lanham says, warning, "A lot of businesses are going to go out of business if he's elected."
About 100 people have gathered amid displays of Western garb and outdoor gear at Bass Pro Shops in suburban Denver for a chance to hear the man billed as the "First Dude" of Alaska. Stuffed elk and deer heads are mounted on the walls and a two-story-high waterfall cascades over rocks in the center of the cavernous space.
Palin arrives wearing a black Tesoro Iron Dog jacket — he has won Alaska's grueling 2,000-mile snowmobile race four times — and surrounded by Secret Service agents.
"I would just encourage you to vote … and take all your hunting buddies and your fishing buddies to the polls," Palin says. He stands on a platform in front of the waterfall and speaks for about five minutes before signing autographs. The last month and a half of campaigning has been "pretty crazy for the Palin family," he says, but adds with a chuckle, "When Sarah decides to do something, you best just get out of the way."
Chuck Staudinger, 63, of Arvada, applauds. He has deep roots in Colorado — his great-grandfather settled here in the 1870s — and he has his own theory why the state's politics are shifting.
It's the newcomers, he says.
"A lot of Californians came in and they brought their California ideas with them," he says. In his own neighborhood, recent arrivals from the Golden State have raised a fuss about paving a dirt road he thinks is fine as it is.
"There are a lot of transplants … and that's really changing the face of Colorado," agrees Sean Feran, 34, a firefighter from Broomfield who is balancing his 3-year-old son, Owen, on his shoulders. "We used to be completely Republican, and now it seems like we're half-and-half. My neighbor on one side is voting for Obama, and the one on the other side is voting for McCain."
A Brookings Institution analysis of IRS data concluded that Colorado, one of the nation's fastest-growing states, has gained nearly as many migrants from California since 2000 as from every other state combined. Many were drawn by the state's tech boom in the 1990s. Now more than one-third of Coloradans are college graduates, fourth-highest in the country.
Those demographic trends have helped shape its political trends.