One of the most surprising outcomes in Tuesday night's early election returns was retired teacher Marty McLaren's lead over Seattle School Board President Steve Sundquist.

On Wednesday she did it again, with an updated vote tally showing her lead nearly doubling.

Members of the Seattle education community spent the day pondering the reason for McLaren's success, debating theories such as that Sundquist, as the board president, may have taken a harder hit than his colleagues for a recent financial scandal in the district.

But the answer may lie in a large but mostly under-the-radar effort by the Seattle teachers union.

Union officials said Wednesday that they put an unprecedented amount of money and time into McLaren's campaign — support she acknowledges was important to her victory.

"I'm very appreciative and very aware of that," she said.

The 67-year-old, who would become the only member of the seven-member board with teaching experience in Seattle, pledged to bring a teacher's perspective to the board and work to restore support for the classroom.

She said she would act independently.

The updated count showed McLaren leading Sundquist 51.5 percent to 48.1 percent with more than half of the expected vote counted.

Another challenger supported by the union, Sharon Peaslee, pulled within 47.9 percent to Peter Maier's 51.8 percent. The other incumbents, Sherry Carr (54.7 percent) and Harium Martin-Morris (61.2 percent) maintained their large leads.

The union's interest in the School Board race began more than a year ago. In the days after the group reluctantly approved a new teachers contract last September, officials decided to get more involved in district politics, said Jonathan Knapp, vice president of the union.

They identified McLaren early. The former Seattle math substitute teacher (along with another challenger, John Dunn, who ended up losing in the August primary), attended a May "training" session that offered tips on building a campaign organization, Knapp said.

After that, the union took a more hands-off approach, he said.

"I wasn't her campaign manager; I didn't have anything to do in the direct day-to-day operations of her campaign," he said. "What our project did was to identify people who shared values around the common project of public education and help to develop them."

While McLaren did not specifically label herself as a union candidate, she benefited from the union's help with phone banking, direct mailings and fundraising

McLaren ended up raising $27,000 for the campaign — significantly more than any other challengers in the race (Michelle Buetow was second, with $19,000). At least half of that came directly from unions, including $9,000 from the state teachers union.

While the Seattle union has mostly chosen to stay out of School Board politics, teachers unions across the country have shown they can greatly influence board races, said Robin Lake, associate director of the Center on Reinventing Public Education at the University of Washington.

"The union can mobilize a lot of teachers to make calls and knock on doors to unseat someone," Lake said.

Knapp declined to take credit for McLaren's apparent victory, but he said his effort made an impact.

He added that he is excited for her to join the board.

"There's going to be a clear voice on the board from the perspective of a classroom teacher," Knapp said. "I think that's going to be a major shift in the process."

He predicted the relationship between the board and the union would improve, although he cautioned change would not be immediate.

"Does that change things automatically and all of a sudden the board's under SEA (Seattle Education Association) control? Of course not. That's ridiculous."

Brian M. Rosenthal: 206-464-3195