When Obama campaign volunteer Alexander Williams went knocking on doors in Portland, Ore., last summer, laying the groundwork for this fall's election, he quickly found reason to worry.

Here he was in a liberal neighborhood, in one of the country's most liberal cities, and known Obama supporters were shutting their doors on him, saying they planned to scrap their presidential ballot. Barack Obama, they said, had capitulated to Republicans.

"People were very, very frustrated. Frustrated to the point where I thought we might go purple because the left wasn't going to turn out to vote," Williams said. "If people in Multnomah County stay home, then the state goes red."

Portland, in the heart of Multnomah County, is famously left-wing, just as ribbed for its bicycle-riding, organic-beer drinking, vegan hipsters as it is admired for its urban-growth boundaries, progressive medical laws and light-rail system. (Where else would an Occupy protester go on a hunger strike to fight for the rights of homeless people and end his 55-day fast with a bite of a locally made vegan doughnut?)

With a population approaching 600,000, four times that of the state's next-biggest cities of Eugene and Salem, Portland is what pushes this otherwise conservative state into the blue zone every four years -- or at least it has since 1988. Although sometimes it's been close: In 2000, the margin was just 0.4% for the Democratic presidential nominee, Al Gore.

If Democrats on the national stage are concerned that they're losing their base, they need only walk the streets of Portland for a single lunch hour to learn why:

Eating a sandwich outside a downtown cafe one day in July, Mike Cipra, a 38-year-old lifelong Democrat, said this may be the first year he doesn't vote. "It doesn't matter who you vote for. This country is run by corporations," he said. "I think Obama cares, but I don't think there's anything he can do. He's dictated by the people with the money."

Down the street, a 40-something man reading a philosophy book outside a Starbucks shop said he, too, was a Democrat who planned to stay away from the polls for the first time. "I can't imagine there being any difference who gets in the White House," said the man, an applied mathematician for a tech company who asked that his name not be published. "We cannot have a reasonable discussion of the issues.

Mike Cipra of Portland, Ore. © Microsoft

Mike Cipra of Portland, Ore.

"In the past, I felt my vote would have an impact, no matter how minuscule, but now I don't have that much faith in the process," he added. "Any positive change in our society will come at the individual level, or the very local level, and this will happen no matter who gets into office."

A few steps away, eating lunch in Pioneer Courthouse Square, another middle-aged professional said he, too, would take his first pass. The man, also requesting anonymity for professional reasons, campaigned for Democratic presidential nominee John Kerry in 2004 and voted for Obama in 2008.

But Obama, "basically didn't fulfill his campaign promises," he said. "He hasn't even tried to move in those directions." The president didn't label genetically modified foods and failed to hold either "torturers" or banks accountable. "He doesn't get my vote, but nobody else does either," he said.

'Frustration . . . not apathy'

But the Democratic Party of Oregon says it isn't too worried. The state has been gravitating further to the left in recent years, in part due to the influx of young college graduates, and its seven electoral votes are expected to go to Obama.

Plus, state party Executive Director Trent Lutz says, "At end of the day, that frustration will definitely turn into a vote" three months from now. "While there's frustration, there's definitely not apathy."

But Portlanders are still worth listening to, if not for just their insight into the growing dissatisfaction on the left, then also because, like it or not, these voters may be on to something. What these liberals are doing in their hometown -- taxing corporations, regulating growth, funding public works, helping the homeless -- appears to be working for them in the 21st-century economy.

"Portland actually has a lot of those things that conservatives would say is the absolutely wrong way to do it," Lutz said. "It can actually be an anchor for 'Here's how it can work and how it can be a success story.'"

For local manufacturer Oregon Iron Works, Portland's eco-friendly business climate has meant millions of dollars in new contracts and the creation of its subsidiary United Streetcar, which is now building the first U.S.-made streetcars in 60 years.

"We probably have over 100 companies in Oregon that help build these streetcars," company Vice President Chandra Brown said. Seventy percent of the cars' materials are manufactured in the U.S.

"Opportunity can be created through some of these green initiatives," she said. "It's not a net loss."