Democratic challenger Eric Swalwell was well ahead of independent challenger Chris Pareja for the right to take on Rep. Pete Stark in November's general election for the newly drawn 15th Congressional District, early returns showed Tuesday.

Swalwell was off to a such a strong start that he could pose a significant threat to the 20-term incumbent Stark, D-Fremont, come this fall.

Elsewhere in the Bay Area, Ricky Gill was handily dispatching fellow Republican John McDonald to finish second behind Rep. Jerry McNerney in the new 9th Congressional District. In fact, Gill's and McDonald's combined votes in early returns were adding up to more than those garnered by McNerney, D-Stockton, though a spokeswoman said he's confident of victory come November. Gill is among national Republicans' "Young Guns," and McNerney is wearing the bull's-eye.

The battle to replace retiring Rep. Lynn Woolsey, D-Petaluma, in the new 2nd Congressional District -- stretching from the Golden Gate Bridge to the Oregon border -- looked to be shaping up as a showdown between Assemblyman Jared Huffman, D-San Rafael, and Republican Daniel Roberts, an investment firm CEO from Tiburon; next among the 12 candidates was activist and author Norman Solomon of Inverness.

And, close to the Bay Area, another "Young Gun" -- Colusa County Supervisor Kim Vann -- was leading three other Republicans to finish second behind Rep. John Garamendi, D-Walnut Grove, who had a majority

of the vote in early returns.

In the 15th District, Stark, 80, was leading the vote in early returns. Swalwell, 31, a Dublin councilman and Alameda County prosecutor, was close behind while Pareja, 40, a conservative businessman from Hayward was trailing.

"We survived this first heat, we're moving on, and we kept the incumbent under 50 percent," an elated Swalwell said Tuesday night. "A lot of Democrats may have voted for Stark because that's what they knew, but we're confident that in six more months we can talk to them and earn their votes as well."

It might have been better for Stark if Pareja had made the cut instead of Swalwell. It's hard to imagine any voters who backed the tea party-friendly Pareja will leapfrog over the somewhat more moderate Swalwell to embrace Stark, a liberal paragon, in November. Swalwell, meanwhile, will continue trying to chip away at Stark's Democratic base even as he tries to win over those Pareja voters.

He'll definitely be appealing to the "anyone but Stark" bloc, which might have grown as Stark made ill-researched public accusations recently that Swalwell had taken bribes in exchange for favorable Dublin zoning decisions; money from developers with legal problems; and a contribution from a newspaper columnist. None were true, and Stark's apologies seemed to play into Swalwell's narrative that Stark has been in Washington for too long and has lost touch with common folks in his district.

Although Stark is a 20-term incumbent, he contends he still has more to accomplish, including protecting Medicare and Social Security for future generations; cutting military spending, including ending the nation's current wars while avoiding new ones; advancing education bills for disadvantaged children; and bringing more federal funding to district infrastructure projects.

In the 9th District, Gill, 25, who received a UC Berkeley law degree last month, is emphasizing his local roots as a Lodi native; his work in his family's vineyard and RV-park businesses; and his service as a former student member of the state board of education. McNerney, 60, is seeking a fourth term after focusing on veterans' issues, growing the local economy and protecting the Delta's water resources. He recently moved from Pleasanton to Stockton.

McNerney campaign spokeswoman Lauren Smith said Tuesday that primaries tend to bring out more partisan voters, and she's confident the incumbent has "a clear path toward victory in the general election" in a district that President Obama won by an 18-point margin in 2008.

In the 2nd District, Huffman, 48, is a former public interest consumer attorney who has crusaded for environmental causes during his six years in the Assembly, leading both the Water, Parks and Wildlife Committee and the Assembly Environmental Caucus. Roberts is the founder and CEO of San Francisco-based Roberts & Ryan Investment Inc.

Elsewhere in California, two long-serving Democrats are headed for a November showdown in a bitterly contested Los Angeles County House district.

Reps. Howard Berman and Brad Sherman were closely matched in their fight for the 30th District seat in the San Fernando Valley, a race that has seen more than $5 million in spending. According to early returns, Sherman grabbed about 40 percent of the vote, to 34 percent for Berman. Several Republicans trailed far back, meaning the two Democrats would face off again in November.

In a statement from his campaign, Sherman said the tally Tuesday was "preparation for a victory party in November."

In the narrowly divided 10th Congressional District in central California, Republican Rep. Jeff Denham locked up a November runoff with former space shuttle astronaut Jose Hernandez, a Democrat. Chad Condit, who stressed his independence from traditional political parties, lagged in the single digits; he's. He is the son of former Rep. Gary Condit, who was ousted when his relationship with a Washington intern emerged after her disappearance.

In Ventura County, Supervisor Linda Parks was trailing two other candidates in her bid to claim the 26th Congressional District seat running as an independent. The fastest growing political affiliation in California is "no party preference," and independents now make up about 21 percent of the statewide electorate, and 19 percent of voters in her district. If elected, Parks would become the only independent in California's congressional delegation. But Republican Tony Strickland was leading with 45 percent of the vote, with about 40 percent of the precincts reporting, followed by Democrat Julia Brownley, with 26 percent. Parks had 19 percent.

New district boundaries drawn by an independent commission -- a power once held by state lawmakers and party insiders -- opened the way for competitive contests. Nine of the 53 districts have no incumbent on the ballot, and the open seats have lured a throng of competitors.

With control of the House of Representatives on the line, national Republicans fear California is among the states where they could lose ground, even if it's a longshot for Democrats to pick up the 25 seats they need to reclaim the majority.

The level competition is unfamiliar in California, where for years political deal-making produced districts that virtually guaranteed one-sided results on Election Day. Only one House incumbent lost in California in the last decade, a period when voters grew increasingly disillusioned with Washington.

The Associated Press contributed to this report. Josh Richman covers politics. Follow him at Read the Political Blotter at