When Democratic and Republican presidential or vice-presidential candidates come to the area for their campaigns, they fly in on Air Force One, or something like it, and they ride in motorcades, sometimes slowing traffic for miles.

When Judge Jim Gray, the Libertarian Party vice-presidential candidate, came to speak at Stanford, Greg Coladonato picked him up from the airport in his car. The two men had never met.

Coladonato is the Silicon Valley coordinator for Libertarian Gary Johnson's presidential campaign, and he said this kind of contrast is a symptom of a problem in the U.S. political process.

"Let's start with the fact that the political system is completely co-opted with a duopoly to the extent that third-party candidates can't even get into a debate with the two candidates," he said. "I'd like to see more choice afforded to the electorate rather than, 'Pick one of these two guys' who, when it comes down to it, aren't that different.'"

Coladonato said he's politically active in the area, mainly hosting and attending events for Johnson's campaign. He said he hasn't heard of any area Libertarians traveling to battleground states to campaign for Johnson.

"Every state has its own activists," he said. "For us there are no swing states, so there's not much reason to go to Ohio or Florida. Why not just stay where it's more convenient and try to get people there?"

In 2008 Coladonato went to New Hampshire to knock on doors for Republican Ron Paul, who he described as "third-party-esque." He said a similar effort for a third-party candidate could be valuable provided the candidate was popular enough in a state to garner volunteer support.

"I think then you'd see a lot of Californians going to Nevada to knock on doors," he said. "It'd probably be good to concentrate there, where the chances are much greater for Johnson to show double digits in the election, owing to both Nevada's voting habit and to the fact that it's generally easier to change an outcome in a smaller state."

Nevada is home to about 2.7 million people, just 7 percent of California's nearly 38 million.

Gerry Gras, a local volunteer for the Green Party, sees the situation similarly. But he holds different priorities for his party, particularly when it faces what he perceives as a stigma for "spoiling" elections.

"There are a number of people who perceive us as spoilers and would expect us to go campaign," he said. "We're not spoilers. The two major parties aren't solving the problems the average person cares about, and we've got real solutions to them."

Gras sees the group's main goals as getting candidates on the ballot and achieving 5 percent of the total presidential vote, which would give it matching funds for the next election.

That threshold hasn't been reached yet, however. Ralph Nader was the closest with 2.7 percent of the vote in the 2000 election. This year's Green Party presidential candidate is Jill Stein.

Nevertheless, Gras said the party is sponsoring candidates at all levels, from school boards to president. But there aren't a lot of people traveling around to campaign for the party.

He said third-party efforts in California have been hampered by the recently adopted "top-two" election system, in which the two candidates with the most votes in the primary are put on the general-election ballot, regardless of their political affiliation. (The system does not apply to the presidential race but to lower offices.)

"It's been a real hindrance because we don't have so many people on the ballot," he said. "I wouldn't be surprised if people are surprised when they see this year's ballot."