What if you held a presidential campaign, and nobody came?

The question must be burning in the minds of Libertarian presidential nominee Gary Johnson and Green presidential nominee Jill Stein as they continue their dogged campaign tours that brought both to the Bay Area on Tuesday.

Johnson drew a crowd of about 200 -- about half who'd come out for him, about half curious passers-by -- at midday on UC Berkeley's Sproul Plaza. Stein spoke to a crowd of about 120 that evening in a Palo Alto church.

The only way you'd see President Barack Obama or Republican presidential nominee Mitt Romney address crowds so small is if attendees each paid six figures to be there.

Those kinds of events are not Johnson's or Stein's style. Both are quick to say they're not the candidates of moneyed special interests, but rather of ordinary Americans fed up with a two-party system that's either deadlocked or in corporate cahoots, depending on how you look at it.

"It is a perfect storm for political transformation," Stein said. "People are clamoring to have a voice in elections that are not bought and paid for by Wall Street."

But they'd surely like to see bigger crowds. Even as disenchantment with Obama and Romney might run high, third parties and independent candidates in America -- particularly in California -- face an increasingly tough row to hoe.

This year offers none of the national fervor that fed Ralph Nader's Green candidacy in 2000, Ross Perot's independent run in 1992, or John Anderson's independent candidacy in 1980. The much-ballyhooed and well-funded Americans Elect -- a nonprofit, nonpartisan group that tried to hold a national online primary to put a centrist presidential candidate on all 50 states' ballots -- ran aground in May after most well-known potential candidates backed away and not nearly enough voters took part.

In California, Greens now account for 0.63 percent of registered voters and Libertarians for 0.55 percent, and the state's new "top two" primary system means it's about to get much harder for them and other third parties to remain qualified for the ballot.

Yet neither Johnson nor Stein will let numbers get in the way of their messages.

"I think I'm speaking the truth, and it's kind of a great hole card," said Johnson, wearing a suit jacket, a peace-sign T-shirt and jeans while surrounded by supporters at Cal.

He's proud to have vetoed hundreds of bills and thousands of budget line items as New Mexico's governor -- and wants to wield his blue pen just as fervently in the Oval Office. He wants to replace all income, payroll and business taxes with the "Fair Tax" -- a 23 percent levy on all purchases of goods and services with a "prebate" to cover the necessities of life. He wants free-market health care with no government intervention; no gun control whatsoever; an immediate end to the Afghanistan War and no future overseas entanglements. He would turn Medicare and Medicaid into block-grant programs for states to administer as they wish. And he says Social Security is "absolutely savable" by raising the retirement age, enacting means testing and letting people opt into private investment instead.

President Obama talks a good game, but his rhetoric doesn't match reality, Johnson said, citing the Obama administration's crackdown on medical marijuana dispensaries as an example. GOP presidential nominee Mitt Romney, he said, is foolish to demand a U.S.-Mexico border fence and keeps pitching budget numbers that just don't add up.

Johnson and Stein are in agreement about legalizing marijuana and ending the drug war; legalizing same-sex marriage; protecting abortion rights; cutting military spending; immediately withdrawing from Afghanistan; and protecting civil liberties, including repealing the Patriot Act.

But whereas Johnson is for austerity, small government and free markets, Stein favors beefing up public employment -- a "Green New Deal" -- to create jobs and improve infrastructure, manufacturing, education and other sectors; a single-payer "Medicare for all" health program; free education through college; and government subsidies and intervention to shift the world away from fossil fuels and toward clean, renewable energy.

In Palo Alto, the crowd was quick to applaud Stein's ideas on health care; eliminating nuclear weapons and nuclear power; and her support of the Occupy movement.

Stein, who also gave talks at four college campuses Monday and Tuesday and planned six more for the rest of the week, said students have been especially excited by her message. "It's like giving out candy for Halloween, Christmas and Hanukkah all at once," she said.

"We have the potential to really come up in the polls," she said. "We've already come up from undetectable to 1 percent, then to 2 percent. If we get to the 5 percent threshold, we will get a $20 million grant to begin the next election and hit the ground running."

Johnson and Stein weren't invited to next month's presidential debates because neither has hit the 15-percent threshold in national polls that's required by the Commission on Presidential Debates.

But Stein and her supporters say people shouldn't feel that they're wasting a vote by choosing a third-party candidate.

"The votes belong to us, and we deserve multiple choices," Stein said. "When they say you shouldn't dare to stand up and vote for your values, they're telling you to continue the policy of silence."

Josh Richman covers politics. Contact him at 510-208-6428. Follow him at Twitter.com/josh_richman. Read the Political Blotter at IBAbuzz.com/politics.

NOT AN OBAMA OR ROMNEY FAN? HERE ARE TWO OTHER OPTIONS
Candidate: Gary Johnson
Party: Libertarian
Running mate: Former Orange County Superior Court Judge Jim Gray
Age: 59
Hometown: Taos, N.M.
Education: Bachelor's degree in political science, University of New Mexico (1975)
Experience: Former two-term governor of New Mexico (as a Republican); former construction company CEO
Website: www.garyjohnson2012.com

Candidate: Jill Stein
Party: Green
Running mate: Activist Cheri Honkala of Philadelphia
Age: 62
Hometown: Lexington, Mass.
Education: Bachelor's degree in psychology, sociology and anthropology, Harvard College (1973); Harvard Medical School (1979)
Experience: Physician; environmental health advocate; two-time gubernatorial candidate
www.jillstein.org

WHY MINOR PARTIES ARE ON THE ROPES IN CALIFORNIA
Minor parties have had three ways of staying qualified for the ballot:
1.) They can poll 2 percent of the vote for any statewide race in a nonpresidential general election. But the state's new "top two" primary system -- in which all voters choose from among all candidates of all parties, and only the two candidates with the most votes advance to November, regardless of party -- means minor parties are very unlikely to even make it onto general-election ballots anymore.
2.) They can have at least as many registered members as 1 percent of the previous total gubernatorial vote. About 10.3 million people voted in the November 2010 gubernatorial matchup, so a party would need about 103,000 registered voters to qualify this way. The American Independent and Green parties meet this threshold now, but the Libertarian and Peace and Freedom parties don't. And the less visible all of them become, the harder the threshold will be to reach.
3.) They can gather petition signatures from 10 percent of the state's 17.3 million registered voters -- a practical impossibility for the small, cash-strapped parties.