Voters can forget the traditional Republican-Democratic matchups in at least seven California congressional districts come November. Contenders for those seats will have to do battle against challengers from their own parties.
Democratic Rep. Mike Honda and Republican Rep. Tom McClintock face the most competitive challenges among the incumbents in the intraparty face-offs. Both are longtime players on California's political scene and face their first serious re-election challenges.
California's revamped primary system, approved by voters in 2010, allows the top two candidates regardless of political affiliation to advance to the general election. The idea is to fight polarization by making them appeal to a wider pool of voters.
The state of Washington also has a top-two primary, while Louisiana has a similar system for its general election, followed by a runoff if no candidate wins a simple majority. Other states exploring such a system include Oregon and Montana.
Whether any of it can weaken polarization is not clear. Analysts say name recognition and money are still the biggest factors in an election. The first go-around in California led to moderates winning about half of the same-party congressional races.
Democratic Rep. Eric Swalwell has been the most notable beneficiary so far. He lost in his 2012 California primary, which in years past would have been the end of his candidacy, but placing second meant he advanced to the general election. There, he defeated a fellow Democrat, Rep. Pete Stark, who had served in the House for 40 years.
This year, Swalwell is awaiting the final canvass to see whether he will face a Republican or another Democrat in November.
The top-two primary also has led to unexpected outcomes. Republican Rep. Gary Miller defeated a more moderate GOP challenger two years ago to win a Southern California congressional district that is heavily Democratic. The two Republicans got the top slots because so many Democrats ran in the primary that they split the vote.
Some call California's new system the "jungle primary" to underscore the free-for-all nature of having all candidates running against each other on one ballot, regardless of party.
In California, this year's general election will feature at least seven same-party races among the state's 53 congressional districts. The Honda and McClintock contests have generated the most interest so far. Both men handily finished first in their June primaries, but, like Stark in 2012, they will now go again against the second-place finishers.
Honda, a seven-term Democrat, has used his position on the House Appropriations Committee to help secure federal funding for an extension of commuter rail to San Jose and bring a U.S. patent office to Silicon Valley.
The Center for Responsive Politics estimates that Honda sponsored or co-sponsored some $147.5 million worth of earmarks over a three-year period before Congress banned the practice. Earmarks refer to federal money designated for specific projects, communities and organizations.
But the ban has diminished the Appropriations Committee's influence, and Honda's Democratic opponent, Ro Khanna, says it will take a new way of thinking in Congress to help the region's economy. Among his proposals: Enact national standards that require schools to teach students how to design and write computer programs and change accrediting standards so federal Pell Grants cannot go to schools where graduates struggle to get jobs.
"I really feel like I've dedicated my life to thinking about economic issues," said Khanna, 37, a deputy assistant secretary at the Commerce Department during President Barack Obama's first two years in office. "And I do think I will bring an expertise on the global economy to the United States Congress."
But Honda, 73, said his work is not done.
"I have much more to provide in the future," he said.
The race promises to be one of the most expensive in the country, with Khanna raising $2.6 million before the primary and Honda raising $2.1 million in a district in which Democratic voters outnumber Republicans by more than 2-to-1.
Honda has support from most of the Democratic establishment, including Obama, Sens. Barbara Boxer and Dianne Feinstein, and House Minority Leader Nancy Pelosi.
Khanna's endorsers include former San Francisco Mayor and state Lt. Gov. Gavin Newsom as well as Silicon Valley executives including Google Chairman Eric Schmidt and Yahoo CEO Marissa Mayer.
McClintock's challenge comes from fellow Republican Art Moore, an Iraq war veteran and major in the National Guard.
McClintock dismisses any notion he could have a tough race on his hands, but his campaign was concerned enough about Moore that it sent a mailer to Democratic primary voters to raise the name identification of a third candidate with no party affiliation.
Across the country, tea party conservatives have been challenging establishment Republicans in scores of primary races. This time, it's the tea party incumbent, McClintock, who is getting a challenge from his left.
To win the district that stretches from Sacramento's suburbs to the outskirts of Yosemite National Park, Moore would have to hold his own with Republicans and then pick up the majority of Democrats and independents, who make up 29 percent and 21 percent of the district respectively.
Moore says McClintock is so rigid in his conservatism that he doesn't work to get money to get things done in the district.
"It's being spent in other states and other districts," he said.
McClintock counters that he would "rather restore a system where local money stays local rather than being shipped to Washington."
Dallas Sweeney, chairman of the El Dorado County Republican Party, said the good news about the top-two primary is that a Republican will be in office regardless. While he has endorsed McClintock, he said he hears Republican complaints similar to Moore's.
"You've got to be strong in your principals and core values, but you also have to work to find solutions to make our country great again," Sweeney said.