A dark horse candidate in the San Jose District 3 special election eked out a second place finish in April. Then he trounced his opponent in the June runoff for the City Council seat.

San Jose Planning Commission Chair Anthony Tordillos was able to pull voters from all of the candidates who lost in the April 8 primary, more than doubling his support. His opponent, Latina Coalition of Silicon Valley Executive Director Gabby Chavez-Lopez, only gained about 250 more votes between the April and June elections. Tordillos made significant gains in wealthier downtown neighborhoods, especially near San Jose State University and Northside, while Chavez-Lopez’s support stagnated. Tordillos is scheduled to be sworn in on Aug. 12.

Tordillos won every precinct in the June 24 election, according to official election results certified Thursday. His biggest gain was 417 votes from Naglee Park, a 209% jump from what he received in April, and 270 votes from around Japantown, a 175% increase from April.

Garrick Percival, chair of the political science department at San Jose State University, said Tordillos’ win following Chavez-Lopez’s lead in April likely came down to vote splitting, as the pool of candidates narrowed from seven to two in the runoff. Percival said Tordillos likely captured most of third place candidate Matthew Quevedo’s votes, after the tight race and recount for second. Tordillos beat out Quevedo, deputy chief of staff for Mayor Matt Mahan, by six votes.

“I think the people who didn’t vote for Chavez-Lopez in the first round were perhaps more moderate or the more conservative voters in the district,” Percival told San José Spotlight.

Only 8,366 of District 3’s 47,189 registered voters cast ballots in the June election, meaning the seat was decided by less than 18% of the district’s electorate.

Percival said the low turnout likely had an impact, but it could have gone either way. He said special election voters are typically higher income and more politically engaged, but labor unions also mobilize their bases around special elections.

“It’s a competition of trying to attract your most likely voters, to get them out,” Percival told San José Spotlight. “This is likely not a truly representative sample of District 3 voters because turnout was so low.”

Chavez-Lopez had a commanding lead over her opponents in April. But between then and June, she made much smaller gains and even lost votes in some neighborhoods. Her largest gain was from residents around SJSU, with an extra 55 votes, but she lost 47 votes from residents around Goodyear-Mastic, St. James Park and Northside/Empire Gardens neighborhoods.

Here’s how Tordillos and Chavez-Lopez compared in four key neighborhoods

District 3 has 25 precincts. Tordillos won hundreds of new voters in the June runoff election, while Chavez-Lopez saw modest gains and even lost some votes in certain regions.

Here are four neighborhoods with some of the most significant voter swings.

The Santa Clara County Democratic Party endorsed both candidates. Chair Bill James said they don’t normally analyze an election’s outcome when it’s between two endorsed candidates. While James said he didn’t have specific insights on the race, he pointed out having a broader base of support gives candidates a leg up in special elections.

“You just trust the process at that point,” James told San José Spotlight. “The process chooses someone who will be good because they’re both good candidates.”

James speculated the mayor’s endorsement of Tordillos after the April election may have had a large impact, as most voters flocked to Tordillos in the runoff. He said while Chavez-Lopez received a similar number of votes between April and June, he’s unsure if they were the same voters.

Tordillos said he’s proud his campaign gained support across various communities, including the county’s Democratic Party, labor unions and business groups, despite being outspent by special interests.

“After how close the primary was, we knew we had to work hard for every vote and not take a single voter for granted,” Tordillos told San José Spotlight. “I look forward to hitting the ground running in a few weeks to restore trust in city government and make progress on District 3’s most pressing issues.”