Democrat Lena Gonzalez defeated Republican Jack Guerrero Tuesday in a special election to choose a new state senator to represent communities along the 710 Freeway in southeast Los Angeles County.

Once the results in the 33rd District race become official, Gonzalez will replace Ricardo Lara, a Democrat from Bell Gardens who had two years left in his second term in the Senate when he was elected California insurance commissioner last November.

With 100% of precincts reporting at about 11:45 p.m. Tuesday, Gonzalez had 69% (26,343 votes) to Guerrero’s 31% (11,835), according to L.A. County’s election webpage.

“I’m grateful to all of my supporters for the hard work they’ve put into this campaign,” Gonzalez said. “But the work is just beginning. Now we have the opportunity to get to work for the residents of the 33rd District and for all of California.”

Tuesday’s election capped a campaign that began in earnest in December when Gonzalez, a second-term city councilwoman in Long Beach, announced she was running for the open seat.

She was considered the front-runner almost from the start. Gonzalez picked up early endorsements from Lara, Long Beach Mayor Robert Garcia and other key Democrats. After Long Beach City Councilman Al Austin ended his brief campaign Feb. 1, Gonzalez was the only major candidate from the district’s biggest city and the best-known Democrat in a majority-blue district.

The 38-year-old Gonzalez came in first in the March 26 primary against eight other Democrats, two Republicans and one Green Party member, a field that included city council members from South Gate, Bell, Lynwood and Cudahy. But her 31.6% of the vote fell far short of the 50%-plus-1 a candidate needed to avoid a runoff.

Guerrero, 45, a second-term councilman from Cudahy, qualified for the runoff by finishing second in the primary with 14%, taking advantage of the fact there were only two Republican candidates to split conservative support.

Before the primary, Gonzalez faced criticism when the Press-Telegram reported that she had been arrested for drunk driving in 2012, when she was an aide to Garcia, then a city councilman. Gonzalez had pleaded guilty, paid $900 in fines and fees, and completed 49 hours of community service and a three-month alcohol education program for first-time offenders. The case was dismissed in January.

“It happened seven years ago,” Gonzalez said in an interview in May. “It’s something that’s a huge regret in my life. It was something I took care of and eventually got dismissed. All you can do is learn from these things.”

Gonzalez also had to fend off jabs from primary opponents and Long Beach-area environmentalists after oil and gas industry interests made $1 million in independent expenditures for campaign advertising on her behalf. She pointed out that candidates don’t solicit such independent support, and noted that the same petroleum interests could turn around and spend money against her in the general election. (They didn’t.)

In the runoff campaign, Gonzalez and Guerrero focused on their dramatically different views of the issues.

Guerrero, a Stanford- and Harvard-educated economist and CPA who boasted a record of enacting clean-government measures in two terms on the Cudahy City Council, promoted efforts to help California business by cutting taxes and regulations, rein in public employees’ pensions and reform education by pushing school vouchers.

Guerrero told voters in Cudahy and elsewhere in the northern end of the district that they should elect him to make sure their new senator pays as much attention to them as to Long Beach residents.

The district of more than 900,000 residents covers post of Long Beach and the cities of South Gate, Lakewood, Lynwood, Huntington Park, Paramount, Bell Gardens, Bell, Maywood, Cudahy, Signal Hill and Vernon and a sliver of L.A.

Gonzalez, one of two children of a Mexico-born mother and U.S.-born father, went to Saddleback College and Long Beach State and earned an MBA from Loyola Marymount while serving on the Long Beach City Council. She is a corporate-affairs manager for Microsoft, overseeing its L.A. philanthropic portfolio.

Her campaign emphasized environmental cleanup, support for public schools, affordable housing and tenant protections, and expanding access to health care.

Gonzalez will leave both her City Council and private-sector jobs to join the Senate.

Long Beach City Clerk Monique de la Garza said that if Gonzalez won the Senate election Tuesday, a special election to fill her 1st District seat on the City Council would be held sometime in November. The city charter requires an office to be filled within 120 days of the council member’s departure. The mayor could appoint a temporary replacement to serve in the meantime.

Although all 192 precincts reported results to election officials Tuesday night, the count won’t be complete for at least several days because mail-in ballots can be received by the L.A. County Registrar-Recorder as late as Friday as long as they were postmarked by election day. Mail-in ballots cast in the four weeks leading up to election day typically account for most of the votes in California races.

County officials have until June 14 to send certified results to the California Secretary of State. whose office has until July 12 to certify the winner.