won the district in 2004 with 61.3% of the vote. John McCain carried the district in 2008 with 53.98% of the vote while Barack Obama received 43.83%. As of 2006, Republicans had 48 percent of voter registrations, Democrats had 30 percent, and Libertarians had roughly 5 percent. A Democratic congressional candidate nearly won the district in 2008, losing by only half a percentage point and less than 1,600 votes, indicating that the district was much more competitive than it appeared to be. But in the more recent 2012 and 2014 elections the Republican candidate won over 60% of the vote indicating the District remains solidly Republican. New district boundaries for the 2012 elections shifted the population center to the south and east. Registered Democrats and Independents/Decline to State voters in the new district area outnumber registered Republicans by 12%. However Republicans, Independents/Decline to State and small third parties outnumber Democrats well over a 2 to 1 ratio. There are 183,800 Republicans, 117,300 Democrats and 97,200 other. While 2018 saw 7 of California's Republican held House seats fall to Democrats, Republican Tom McClintock held his district by more than 8% over Democrat Jessica Morse.
In 2018, six Democratic candidates filed statements of candidacy with the Federal Election Commission. They were, in alphabetical order by last name: ; ; Richard Martin; Robert Lawton; ; and . Martin and Wilcox dropped out of the race, with Wilcox endorsing Morse in February. Retired Air Force Lieutenant ColonelCharlie Brown, who was the Democratic nominee for this seat in 2006 and 2008, was "seriously considering" running in 2018, but decided in June 2017 against a third campaign. In January 2018, Brown endorsed Morse for the nomination. Bob Derlet, the Democratic nominee in 2016, also endorsed Morse in January. On the Republican side, McClintock has one challenger, , who filed with the FEC in January. In February, the California Democratic Party endorsed Jessica Morse in a contested Democratic Nomination. Roza Calderon was able to successfully collect 322 California Democratic Party credentialed delegate signatures needed to block endorsement, in which Morse only received 44 delegate votes. However, CDP staff refused to accept the forms after it was alleged they closed doors early to prevent the submission. A petition was later filed with the Compliance Review Commission by Roza Calderon. The CRC voted to accept and count the signatures, ultimately disqualifying enough signatures to proceed with the endorsement of Morse. California allows candidates to include their professional description under their names on the ballot. Regina Bateson challenged Morse’s ballot designation title of “National Security Fellow” at the Sacramento Superior Court after months of controversy that Morse, who had not worked in 3 years, was fluffing her credentials. California's Secretary of State, Alex Padilla, had struck down Morse's 3 ballot designations before Judge Gevercer ruled that she presented “no credible evidence” to use the ballot designation of “National Security Fellow.” Instead, he held that this title would mislead the average person about her recent activities." The official Certified Candidate List, Jessica Morse's ballot designation was left blank. The California jungle primary system means that only the two candidates with the most votes on June 5, regardless of party, will go on to the general election on November 6. Both Republicans and four Democrats appeared on the jungle primary ballot. Morse finished second in the Nonpartisan blanket primary in June 2018. Morse was denied "National Security" as her ballot designation for the November ballot. In the November general election, McClintock held the district with an 8+ advantage.
