DeMaio was a candidate for Mayor of San Diego in the 2012 election, but lost to former congressman Bob Filner. He was a candidate for California's 52nd congressional district in the 2014 election, but lost to incumbent Scott Peters.
DeMaio was born in 1974 in Dubuque, Iowa to a pair of teachers, Carl Joseph DeMaio and Diane M. DeMaio (née Elgin). His family moved to Orange County, California in the late 1970s. He attended St. Catherine's Military Academy, a Catholic school in Anaheim, through eighth grade; in 1989 he got a scholarship to Georgetown Preparatory School in Maryland. His mother died in 1990; his father is estranged. He graduated from Georgetown Prep in 1993, then attended Georgetown University, where he received a degree in International Politics and Business.
While attending college, DeMaio worked as a political intern in Washington, D. C., then worked for the Congressional Institute, serving as the Institute's Director of Planning. He worked in Washington from 1994 to 1999. After college, he established The Performance Institute, a for-profit think tank that provided training for government officials, followed by the American Strategic Management Institute, which provided financial and management training to corporations. He sold both companies to the Thompson Publishing Group in late 2007.
DeMaio moved to San Diego in 2002. That year he appeared on behalf of the Performance Institute in front of the San Diego City Council to present an award to the city for having the most efficient government in California. He later alleged this award was based on "false and misleading" financial data provided to him by the city.
In 2004, the Performance Institute claimed that San Diego's predicted budget deficit of $27 million was in fact closer to $80–$100 million. DeMaio has advocated for change in San Diego's budget process.
In April 2015, DeMaio joined KOGO to co-host a radio show with Bob Sullivan.
DeMaio ran for the termed-out Brian Maienschein's District 5 San Diego City Council seat in the nonpartisan 2008 election. At the time, District 5 included the neighborhoods of Rancho Bernardo, Carmel Mountain Ranch, Sabre Springs, Mira Mesa, Sorrento Mesa, Scripps Ranch, and San Pasqual Valley.
He won the seat in the June primary election, defeating his opponent, former Solana Beach Fire Chief George K. George, with 66% of the vote. DeMaio was the first openly gay man to be elected to the council, and the first Italian American elected to office in the city of San Diego since the 1930s.
As a council member, DeMaio was vice chair of three committees: the Natural Resources and Culture Committee, the Budget and Finance Committee, and the Audit Committee.
While a member of the City Council, DeMaio released a number of studies and proposals on city employee compensation packages and pension benefits, arguing that salaries and benefits of city employees should be reduced to levels consistent with the local labor market. He opposed a proposal to build a new San Diego central library, saying the city could not afford it.
DeMaio also proposed a Sunshine Act, which passed the City Council with unanimous support. The ordinance imposed new disclosure and transparency reforms on city government.
DeMaio was the primary author of San Diego's June 2012 Proposition B, entitled "Amendments to the San Diego City Charter Affecting Retirement Benefits," and he led the drive to put it on the ballot. Proposition B proposed (1) limiting of compensation used to calculate city employee pension benefits; (2) eliminating defined-benefit pensions for many new city employees, substituting a defined-contribution (401(k)-style) plan; (3) requiring substantially equal pension contributions from the City and employees; and (4) eliminating the right of employees/retirees to vote to change their benefits. Proposition B was approved by San Diego voters by a 2-to-1 margin on June 5, 2012.
In 2010, DeMaio supported the addition of a citizen initiative called "Competition and Transparency in City Contracts", which would require the city to seek competitive bids for some services and allow the city to outsource without the involvement of unions. However, the measure was rejected by the county registrar of voters after a random sample concluded that DeMaio had not gathered enough valid signatures. After the ballot measure was rejected, San Diego CityBeat reported that a committee called "Reforming City Hall with Carl DeMaio" had paid $16,000 to Hale Media Inc., a company owned by DeMaio’s boyfriend, for signature gathering. When CityBeat contacted Johnathan Hale, he said he hadn’t done any paid work for the campaign, but had only volunteered and taken photos. A campaign spokesperson said the money was reimbursement to Hale Media for paying the interns who were collecting signatures.
DeMaio also campaigned against a proposal to boost the city's sales tax by a half-a-billion dollars over five years. He argued instead to reduce the budget deficit through spending cuts and pension reform.
In 2011, DeMaio filed papers declaring his intention to run for Mayor of San Diego in 2012, when mayor Jerry Sanders would be retiring due to term limits.
In June 2011, he formally declared his candidacy. He was endorsed by the San Diego County Republican Party in March 2012. In the June 5 primary he placed first with 31.42% of the vote and advanced to a runoff election against U.S. Representative Bob Filner in November.
The U-T San Diego published a front-page endorsement of DeMaio before the June 2012 primary. The Voice of San Diego described the endorsement as unprecedented: "Actually, they weren't even on the front page — the editorials were wrapped around the page as though they were even more important."
On September 25, 2012, Sanders endorsed DeMaio to be his successor. At the time of the endorsement, a 10News and SurveyUSA poll of voters gave Filner a twelve-point lead over DeMaio.
On Election Day, DeMaio lost to Filner, 52.5% to 47.5%.
On May 30, 2013, DeMaio announced his intention to run for Congress in 2014 against incumbent Scott Peters.
DeMaio was one of three openly gay Republican candidates for Congress in the 2014 elections. In February 2014, he became the first congressional candidate to feature his same-sex partner in a campaign ad.
In September 2013, he considered running for Mayor of San Diego in a November 2013 special election, called because of Filner's resignation, but decided to stay in the race for Congress. In the June 2014 primary, he came in second to Peters with 36% of the vote, ensuring DeMaio a place on the ballot in the November 2014 general election. Peters received 42% of the vote.
In a poll conducted by SurveyUSA for the San Diego Union-Tribune and 10News during September 11–15, 2014, DeMaio and Peters were in a virtual dead heat with Peters polling at 47% and DeMaio at 46%. The same poll taken October 2–6 was again described as a dead heat, with DeMaio showing a 3-point lead over Peters – within the margin of error. An earlier Survey USA poll showed Peters leading by one point.
The National Republican Congressional Committee elevated DeMaio to “On the Radar” status, which gives candidates the “tools they need to run successful, winning campaigns.” The San Diego Union-Tribune endorsed DeMaio.
DeMaio received the endorsement of Tom Hom, the first Asian-American San Diego City Council member, the Howard Jarvis Taxpayers Association, the Mexican American Business & Professional Association, and the National Federation of Independent Business. DeMaio's campaign was supported by John Boehner, Mitch McConnell, and Michael Bloomberg. The U.S. Chamber of Commerce declined to endorse DeMaio.
In October, the former campaign policy director of DeMaio's campaign, Todd Bosnich, charged DeMaio with sexual harassment, saying that DeMaio had masturbated in front of him and touched him inappropriately. DeMaio denied the allegations, saying they were made after Bosnich had been terminated for plagiarism and subsequently vandalized campaign headquarters.
A similar accusation had been made in August 2013, when former City Council colleague and political opponent Ben Hueso claimed that he had twice seen DeMaio masturbating in a public restroom; DeMaio dismissed that allegation as a "vicious rumor." On October 20, the San Diego County District Attorney declined to file charges against either DeMaio or Bosnich. At the same time, it was reported that the FBI was investigating various claims by Bosnich, separate from his sexual harassment allegations against DeMaio.
In June 2015, Bosnich admitted that he had faked threatening emails he claimed were from DeMaio, and pleaded guilty to one count of obstruction of justice.
In early November, another former staffer, Justin Harper (then aged 25), accused DeMaio of sexual misconduct inside a bathroom at DeMaio's campaign headquarters. DeMaio denied the accusations, saying they were orchestrated by his opponent's campaign.
Although DeMaio led by 751 votes on election night, about 148,000 provisional and mail-in ballots remained to be counted. By the end of the week, Peters led the race by nearly 4,500 votes, with only 10,000 ballots left to be counted. At that point, the Associated Press called the race for Peters. The final result was Peters 51.59% and DeMaio 48.41%.
DeMaio has said that healthcare reform is necessary, but that the Affordable Care Act “as written will not work." He has stated that his reform proposals include allowing individuals to buy health insurance across state lines and putting the government exchanges under private management.
He has stated his intent to propose a “No Budget, No Pay" law that would permanently penalize the pay of Members of Congress and political appointees in the White House when they fail to pass a budget on time.”
On gun control, DeMaio has stated that he supports “full enforcement of existing laws as well as more resources to keep guns out of the hands of criminals and those with mental health disorders.”
According to the National Journal, he “has voiced support for gay marriage, abortion rights, and environmental protections.”