The 32½-point margin of victory in Danville Mayor Candace Andersen's win Tuesday over college board President Tomi Van de Brooke in the Contra Costa supervisor election is a stunner.

Internal polling reportedly showed Andersen's strong ballot designation -- mayor and attorney -- gave her a boost but "not 30 points worth," one political consultant observed wryly.

Some of those points were undoubtedly due to Andersen's higher name recognition in the San Ramon Valley, where she has held public office for nearly a decade and where the population outnumbers the northern part of the district in Lamorinda.

But other than a handful of precincts in Van de Brooke's hometown of Orinda, Andersen won, and won big everywhere.

What happened?

Record-low turnout in a presidential primary was clearly a factor.

Van de Brooke's campaign strategy relied on 40 percent turnout, and the county will be lucky to come within a few points of that figure. She and her supporters poured considerable effort and money into the week leading up to the election.

By then, however, many voters had already cast ballots by mail and insufficient numbers showed up at the polls to fill the gap.

Van de Brooke and her supporters also seriously miscalculated how much social issues matter to voters in a supervisor race, even in a supervisorial district and county dominated by Democrats.

Van de Brooke began telling voters early in the race that she was the only woman in the race who favored abortion rights and same-sex marriage. Democratic, labor and women's rights organizations pounded home the same message in mailers delivered the final week.

To Andersen's credit, her response was direct and pitch-perfect: Yes, she personally opposes abortion and same-sex marriage, but county supervisors have no jurisdiction in either arena, and she has no social issues agenda. She is running, she said, to reform public employee pensions, solve budget problems and create jobs.

Her decision to focus on pension reform was fortuitous as well.

The debate over the appropriate benefit levels for public employees has ramped up across the country as government agencies suffering revenue losses cut services.

Voters in San Jose and San Diego on Tuesday approved pension measures that, if they hold up in court, require current employees to either pay more out of their pockets or receive reduced benefits.

The benefit is impossible to quantify, but Andersen also used social media at unprecedented levels in a local supervisor campaign -- sophisticated website, email blasts, scannable bar codes on campaign materials linking to a website, and Facebook and Google ads.

It came about for two reasons, she said. Her Google-guru son, P.J., was up to the task, and social media is less expensive and more nimble than traditional mail.

In the final week, when her opponent's critical mailers hit the streets, Andersen said she didn't have the money or the time to respond with her own printed materials. However, she was able to buy Internet ads and blast responses.

Watch for Andersen's successful social media strategy to catch on in November's local races where candidates typically have less money to spend.

Van de Brooke says she hasn't decided yet if she will be run for re-election to the Contra Costa Community College District governing board.

With the supervisor race decided, she's looking for a job, and its demands may preclude continued service at the college.

Understandably, Van de Brooke is disappointed in the outcome. If she could have made it into the November runoff where Democratic voter turnout will be stronger, her chances would have been higher.

But to her credit, she called the campaign a "wonderful experience" and expressed heartfelt gratitude to her volunteers.

"I was so blessed to meet so many wonderful people who came out and supported me -- people who will become longtime friends that I didn't even know before the campaign," Van de Brooke said.

Voters owe both women a big thanks.

Granted, it wasn't a perfect campaign. Van de Brooke and her supporters pushed too hard on wedge social issues and failed to pick up on what voters really cared about in a future supervisor.

But running for local office is an incredibly stressful competition for which the grand prize is four years of incessant public criticism, second-guessing by armchair political consultants (aka newspaper reporters) and Saturday night rubber-chicken dinners.

These women know all this, yet they came enthusiastically to the race.

They had relevant experience. They shared their policy ideas. They raised money and ran serious campaigns.

Most important, they debated each other in numerous public events and allowed voters to compare them side-by-side.

We should not only thank these women, but demand even better from the November candidate crop.

Contact Lisa Vorderbrueggen at 925-945-4773, lvorderbrueggen@bayareanewsgroup.com, IBABuzz.com/politics or Twitter.com/lvorderbrueggen.