They’ve been a colorful part of California’s political landscape for decades — Greens, Libertarians, American Independents and members of the Peace and Freedom Party.

But after Tuesday’s election, most of them will be all but invisible — and perhaps on their way to extinction.

In past years, minor parties held their own primary elections to choose nominees who would go on to compete with Democratic and Republican nominees in general elections. But that’s no longer the case under California’s new “top two” primary system, in which all voters choose from among all candidates of all parties — and only the two candidates who get the most votes advance to November, regardless of party.

Because minor party candidates rarely finish in the top two, and it’s now harder for their candidates to get on the primary ballot in the first place, the parties will have little or no presence on the general-election ballot. And in politics, invisibility means oblivion.

“It could spell the end of the Peace and Freedom Party,” said party chairman C.T. Weber, 71, of Sacramento. “It’s a shame that democracy is being undermined by this, but that’s the reality if we’re not able to overturn the law.”

The law was set in place with Proposition 14 in June 2010, approved by 54 percent of voters after then-state Sen. Abel Maldonado, R-Santa Maria, forced the Legislature’s Democratic majority to put it on the ballot in exchange for his budget vote. Though minor parties complained from the get-go that they would be marginalized if not obliterated by the measure, voters liked the measure’s stated purpose: increasing primary voters’ choices in an effort to moderate the harsh political partisanship plaguing Sacramento and Washington, D.C.

Maldonado argued recently that minor parties will get more exposure in the new top-two primary and “if they represent the views of a significant number of voters in a district, they’ll be in the top two. … I don’t care what party you’re from, if you have a message that resonates with the people, they’re going to vote for you.”

But minor-party officials contend that giving voters only two choices in November — with no write-in votes allowed — denies parties an opportunity to spread their messages and hobbles their ability to field candidates in the future.

“It’s not a good situation,” in part because it’s a lot harder to recruit candidates, said Kevin Takenaga, chairman of the Libertarian Party of California.

“The final outcome is going to be the opposite of what people expect because it’s going to force people to these established candidates — the ones who have more money and more major-party support,” he predicted.

“This is the United States of America, where we have more choices in what type of soft drink you want to drink or restaurant you want to go to than political parties and candidates,” added Takenaga, 39, of Sunnyvale. “Why do we insist on having fewer choices?”

Minor parties have had three ways of staying qualified for the ballot. First, they can poll 2 percent of the vote for any statewide race in a nonpresidential general election. With little or no presence on general-election ballots anymore, though, this will be almost impossible.

The second way is to 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.

The third route — gathering petition signatures from 10 percent of the state’s 17 million registered voters — always has been impossible for the cash-strapped parties.

American Independent Party chairman Mark Seidenberg, 65, of Aliso Viejo, said his party’s registration is robust enough that he’s not worried about staying on the ballot, but he agreed it would be “a shame” for voters to be denied the choices afforded by other parties.

Richard Winger, who edits the Ballot Access News blog, is still optimistic courts will overturn Proposition 14’s obstacles to third-party access. But California already is seeing the effects, said Winger, 68, of San Francisco: About a quarter as many minor-party candidates filed for state legislative and congressional offices this year than in 2010.

That’s because the Secretary of State’s Office interpreted Proposition 14 to void the old system by which minor-party candidates could gather 150 signatures in lieu of paying the primary-election filing fee. Now, he said, they must gather the same number of signatures as a major-party candidate: 1,500 for an Assembly seat, 3,000 for a state Senate or House of Representatives seat.

Washington state’s voters OK’d a top-two system in 2004, but it was declared unconstitutional by the 9th U.S. Circuit Court of Appeals in 2005 before being reinstated by the U.S. Supreme Court in 2008.

Unlike in California, Washington voters don’t declare party affiliation when they register, so maintaining party strength that way isn’t an issue. But Jody Grage, chairwoman of that state’s Green Party, said it has been a tough row to hoe nonetheless.

“Because the primary gets a lot less publicity and fewer voters, that makes a big difference in our visibility,” she said, adding that no third-party candidate has advanced to a November election if two major-party candidates already were on the primary ballot.

Election-reform advocate Steven Hill, co-founder of the nonprofit FairVote, said losing minor parties would result in an ever-narrowing political discourse.

“Minor parties tend to be the laboratories for new ideas. They bring issues and ideas into the political discussion that the major parties often ignore,” he said. “That’s the first thing you’re going to lose, and it’s a fairly big loss.”

He said most Democrat-vs.-Republican races end up with candidates battling for a relatively small population in the middle. So with no minor parties to widen the debate, he said, “they’re going to be talking only to that narrow group of swing voters.”

Laura Wells, a 64-year-old Oakland resident who was the California Green Party’s 2010 gubernatorial nominee, hopes the new primary system leads to a backlash that wrecks the two-party system once and for all.

“I think we’re due,” Wells said. “Goodness, how bad does it have to get?”

Josh Richman covers politics. Follow him at Twitter.com/josh_richman. Read the Political Blotter at IBABuzz.com/politics.