DENVER - Four years ago, Barack Obama used this state as both a stage for his nominating convention and a place to show how his new brand of politics could unite young voters, women and minorities to create a winning coalition even in places that normally back Republican presidential candidates.
Now Colorado has become an example of how hard it has been for him to maintain that coalition against the headwinds of a sour economy and his own disastrous first debate performance in Denver.
Republicans and Democrats alike agree that Colorado is a toss-up in this election. Like other battleground states, a slight Obama polling edge before October here has been transformed into a deadlock. That's because independent suburban women - the key demographic in this closely divided state - are taking a second look at Romney. Some analysts see an enthusiasm gap between Obama's supporters and his rival's. And the president's attacks on Romney's wealth may resonate less here than in blue-collar Midwestern battlegrounds like Ohio.
"He should be doing better and he isn't," said independent pollster Floyd Ciruli, a former chairman of the state Democratic Party. "It's the worst (swing) state of the bunch for him; isn't that amazing? It's the place we thought he could use as a model."
Though the state has only voted for a Democratic presidential candidate once since 1968, Obama won it by 9 percentage points in 2008. The president is now tied in most public polls here, as well as nationally.
The Romney campaign tried to capitalize on that dynamic Tuesday night with a high-profile appearance of Romney and his running mate, Paul Ryan, joined by musicians Kid Rock and Rodney Atkins at historic Red Rocks Amphitheater.
"We're in the homestretch now and I think the people of Colorado are going to get us all the way there," Romney told an ecstatic crowd of about 10,000.
Obama responded with a Wednesday afternoon rally before a pumped-up crowd of 16,000 at a Denver park. "We're going to win Colorado again, we're going to win this election, we're going to finish what we started," Obama said before heading to a Las Vegas rally as part of a 48-hour swing through seven battleground states.
His campaign expresses confidence about its chances here, saying it always knew 2008 was an anomaly and this contest would look more like the normal election-year photo finishes in a state evenly divided among Republicans, Democrats and independents.
To prevail in Colorado, the president needs to win back voters like Robin Abrams, 24, one of the suburban female moderates who voted for Obama in 2008.
"Obama seemed promising - something new, something fresh," Abrams said Tuesday from a coffee shop in Englewood, a suburb south of Denver.
But this time around, she'd undecided. She's getting out of college in about a year and isn't sure she'll be able to find a job. She likes Obama's stance on social issues, especially women's health and abortion rights. But she's thinking about her pocketbook, too.
"Socially, I think I'm more Democratic. But economically, I'm not sure. And I want to be sure," said Abrams, who added that she turns off her cellphone sometimes because she's so bombarded by political messages.
The two campaigns are fiercely battling for the votes of the roughly 100,000 undecided voters here who are overwhelmingly nonpartisan women who support abortion rights. The Obama campaign has modeled its approach on Michael Bennet's 2010 U.S. Senate race, in which the Democratic political novice defied the Republican Party by hammering his tea party opponent on immigrants' rights and abortion. Bennet won by less than 30,000 votes.
Laura Chapin, a Democratic consultant, argues that approach ultimately will put Obama over the top. "The demographics still favor President Obama," she said. "This is a young, well-educated state with a majority of women and a lot of Latino voters."
But the state's high levels of education and relative affluence mean that some of Obama's class-based attacks on Romney may not resonate as well.
"Have you ever seen jobs shipped overseas to China from here?" Ciruli said. "We've got no labor unions, we've got minimal old-style manufacturing."
And Republicans contend that the Obama campaign's attempt to paint Romney as an extremist melted away after voters watched him in the first debate, which was widely viewed in Colorado. "That narrative came crashing into reality when they saw that guy up on the debate stage in Denver seeming rational and reasonable," said Ryan Call, chairman of the state Republican Party.
Kenneth Bickers, a political scientist at the famously liberal University of Colorado, Boulder, said Obama also is suffering from an enthusiasm gap. He said that despite two Obama campaign visits here, he sees far less enthusiasm than he did four years ago. "If there's an enthusiasm gap on the Boulder campus, where I am, that's the canary in the coal mine," Bickers said, adding that he believes Hispanics, who are 21 percent of the population here, may not turn out at the same clip as they did four years ago.
Democrats scoff at the notion of an enthusiasm gap, while boasting that their field operation is as strong as ever and could be worth a percentage point or two of the vote. In a sign of its strength, Democrats dramatically narrowed Republicans' advantage in voter registration this summer. Republicans say their own ground game is vastly improved since their low point in 2008.
Denver-based GOP operative Katy Atkinson said that in a state as close as Colorado, the ground game may make all the difference.
"The Democrats have spent a lot of money registering new voters, and those can be the toughest to turn out. So they have the tougher job, but they also have a very sophisticated program," Atkinson said. "If anybody can do it, the Obama people can. But that's the whole question in Colorado."