Primary campaign
The campaign to replace Solis began as soon as her nomination to Obama's cabinet was announced.
State Senator (and former Majority Leader) Gloria Romero, whose 24th State Senate district overlaps the congressional district, became the first politician to express interest in running for the open seat. On December 18, 2008, the day that Solis's selection first became known, Romero said, "I have deep roots, and I would certainly give it every consideration. Definitely, I am interested". The same State Senate seat was previously held by Solis. Of the many possible contenders, Romero said, "I can beat them all". However, on January 8, Romero decided not to run for the seat, opting to try for California State Superintendent of Public Instruction instead.
On December 22, Judy Chu, Chair of the State Board of Equalization, announced that she would run in the special election. She said, "I've decided to heed those calls [of supporters]. I know this district very, very well and I believe the people of this district know me and know I'm very devoted to the San Gabriel Valley". The congressional district makeup was 48% Latino and 13% Asian. She began campaigning heavily, and captured the endorsements of several San Gabriel Valley politicos. (The following month, Chu became Vice Chair of the Board of Equalization.)
On January 8, 2009, State Senator Gil Cedillo announced he was running. He was endorsed by Romero once she decided not to run, and the race was largely viewed as a contest between Chu and Cedillo. Cedillo collected the endorsements of several local mayors.
On January 7, the day before, Emanuel Pleitez, a 26-year-old member of the Barack Obama presidential transition team for the U.S. Treasury Department, had declared his intentions to run. A young banker who left Goldman Sachs, Pleitez is a native of the district. Pleitez ran a more grassroots campaign, relying on a steady flow of volunteers and various individuals making any contribution to his efforts. The Huffington Post said if elected, he would become the second member of the Millennial generation to serve in Congress. By late March, the Pleitez campaign had about 20 full-time staffers and many volunteers; it was also the first campaign of the 32nd Congressional district to open a campaign office, and launched a modern website before any candidate.
By late January, Blanca Rubio, president of the Baldwin Park Unified School District Board of Education, also said she was running. However, she was not mentioned in subsequent press reports about the election. In late March, she said she was withdrawing from the race for family reasons and endorsed Chu.
Others who had been mentioned as possible candidates for the seat included Assemblyman Charles M. Calderon, his brothers Senator Ronald S. Calderon and former Assemblyman Thomas M. Calderon (both Ronald and Thomas Calderon subsequently declined to run and endorsed Cedillo instead), Assemblyman Edward Hernandez (who subsequently declined to run and endorsed Chu instead), Chu's husband, Assemblyman Mike Eng, and former Assemblyman Ed Chavez (who subsequently declined to run and endorsed Cedillo instead). Candidates from outside the congressional district were also permitted by law.
No major Republicans indicated that they would run in the special election. The Republican who were candidates were former Covina mayor David Truax, accountant Jim Hetzel, and business owner Teresa Hernandez. Hetzel and Hernandez were political newcomers, and these were the first Republicans to vie for the seat since 2002.
As the only Libertarian Party candidate, Christopher Agrella, a businessman, was guaranteed to move on to any general election from the primary. Agrella said his top priorities if elected would be to bring about real government accountability, balance the federal budget by cutting out waste, and repeal the federal tax code in its entirety.
Turnout in special elections is almost always low, and support from organized labor was seen as crucial in helping to get out a candidate's vote. On January 26, Chu received the coveted endorsement of the Los Angeles County Federation of Labor. Cedillo replied that he had a long association with the labor movement and that, "At the end of the day, people know me as a public servant who delivers and not as a politician." Somewhat ironically, all of this campaign activity had taken place before there was any official vacancy in the seat, as Solis's confirmation process was being held up in the United States Senate. Solis herself decline to endorse any of the potential replacements for her, although Chu suggested that the congresswoman would prefer her.
On February 24, 2009, the special election finally became a certainty, with Solis's long confirmation process coming to a successful close.
Chu formally announced her candidacy on February 27, stating, "It occurred to me this seat would open, and who could carry on ... [Solis's] desire to represent the constituents?" Cedillo formally announced his candidacy on March 7 at a rally in El Monte.
The first candidates' forum was held on March 19 in Cypress Park, Los Angeles, sponsored by the Southwest Voter Registration Education Project. Only Cedillo, Chu, and Pleitez were invited. By late March, Cedillo and Chu had each raised several hundred thousand dollars and were widely viewed as the frontrunners. A fellow of the Rose Institute of State and Local Government characterized the contest by saying: "When people talk about this race, there's Cedillo and Chu, then there's Pleitez, and then there's everybody else." Through the end of March, Chu had raised $770,000, Cedillo $568,000, and Pleitez $153,000. One political analyst commented ruefully, "It does not take a lot of money in these low turn out races, but that doesn't mean a lot of money isn't going to be spent."
By April 6, the official filing deadline for the primary, twelve candidates had filed for the race, comprising eight Democrats, three Republicans, and one Libertarian. Chu and Cedillo were still considered the front-runners, with each having raised hundreds of thousands of dollars for their campaigns. Judy Chu's task was complicated by the appearance of her cousin-in-law, Betty Chu, a Republican Monterey Park City Council member and former mayor, on the ballot as well. Benita Duran entered the race as the last candidate for the 32nd Congressional district. She was the former deputy district director for Solis' congressional office and staged a grassroots campaign for the seat.
By early May, Cedillo and Chu were battling each other via campaign mailers, with Cedillo putting out attacks on Chu that included unrelated headlines from articles about the 2008 financial crisis. Cedillo also put out a mailer against Pleitez that represented one of the first uses of in American politics of Facebook photographs for opposition research and negative campaigning. Cedillo's material likened Pleitez's socializing to Animal House and accused Pleitez of flashing gang signs. Chu had the endorsement of Mayor of Los Angeles Antonio Villaraigosa. While Solis herself continued to remain neutral, Solis's husband, parents, and siblings all endorsed Chu.