According to The Cook Political Report and Roll Call, the most competitive districts were the 7th, 10th, 26th, 36th, and 52nd; additionally, the 3rd, 9th, 24th, 41st, and 47th were rated as less than safe.

This was the first election using congressional districts drawn by the California Citizens Redistricting Commission.

[3] It was also the first non-special election to use the nonpartisan blanket primary system established by Proposition 14.

As a result, eight districts featured general elections with two candidates of the same party: the 15th, 30th, 35th, 40th, 43rd, and 44th with two Democrats; and the 8th and 31st with two Republicans.

[10] In March 2012, the California Republican Party declined to make an endorsement in the 1st district.

[11] Labor unions Organizations Labor unions Lynn Woolsey Democratic Jared Huffman Democratic The 2nd district is based in California's North Coast and includes Marin County and Eureka.

Regional delegates of the California Democratic Party met in January 2012 but did not endorse a nominee as no candidate received 50 per cent of the vote.

Incumbent Democrat John Garamendi, who represented the 10th district from 2009 to 2013, ran for re-election.

[43] Labor unions Labor unions Organizations Organizations Tom McClintock Republican Tom McClintock Republican The 4th district is based in east central California and includes Lake Tahoe, Roseville, and Yosemite National Park.

Incumbent Republican Tom McClintock, who had represented the 4th district since 2009, ran for re-election.

Incumbent Republican Dan Lungren, who represented the 3rd district from 2005 to 2013 and previously served from 1979 until 1989, ran for re-election.

[11] Labor unions Organizations Labor unions Organizations In May 2016, Babulal Bera, Ami Bera's father, pleaded guilty to two felony counts of election fraud affecting the 2010 and 2012 elections,[71] and was convicted of illegally funneling $250,000 to his son's campaigns between 2010 and 2012.

[89] Incumbent Republican Jeff Denham, who represented the 19th district from 2011 to 2013, ran for re-election here.

Incumbent Democrat Pete Stark, who represented the 13th district from 1993 to 2013 and its predecessors since 1973, ran for re-election here.

[10] Swalwell won the Tri Valley Democratic Club's Straw Poll on February 20.

[11] Labor unions Organizations The 18th district is based in the Bay Area and includes Palo Alto, Redwood City, and Saratoga.

[11] Labor unions Labor unions Organizations Sam Farr Democratic Sam Farr Democratic The 20th district is based in the Central Coast and includes Monterey and Santa Cruz.

[11] Labor unions Organizations Labor unions Devin Nunes Republican Devin Nunes Republican The 22nd district is based in the Central Valley and includes Clovis, Tulare, and Visalia.

[11] Labor unions Organizations Labor unions Kevin McCarthy Republican Kevin McCarthy Republican The 23rd district is based in the southern Central Valley and includes parts of Bakersfield.

House Majority Whip and Republican Kevin McCarthy, who represented the 22nd district from 2007 to 2013, ran for re-election here.

[11] Labor unions Organizations Labor unions Lois Capps Democratic Lois Capps Democratic The 24th district is based in the Central Coast and includes San Luis Obispo and Santa Barbara.

[135] At the California Democratic Party convention, held in February 2012, delegates voted to make no endorsement.

[193] Labor unions Organizations The 32nd district is based in the San Gabriel Valley and includes El Monte and West Covina.

[156] Jorge Rocha, tax accountant[214] Sanchez received the endorsement of the California Democratic Party in February 2012.

[11] Organizations The 49th district is based in northern San Diego County and includes Carlsbad and Oceanside.

[11] Labor unions Organizations The new 51st district runs along the border with Mexico and includes Imperial County and San Diego.

[11] Vargas was predicted to face fellow Democratic state senator Denise Moreno Ducheny in the general election, but he spent some of his funds on mailers to help Republican Michael Crimmins, who he preferred to face in the general election in this heavily Democratic seat.

The 52nd district is based in coastal San Diego and includes La Jolla and Poway.

Republican Brian Bilbray, who represented the 50th district from 2006 to 2013 and previously served from 1995 until 2001, ran for re-election here.

[245] At its February 2012 convention, the California Democratic Party declined to endorse a candidate for the 52nd district.