Spending by outside groups made last year's race between Susan Gorin and John Sawyer for the 1st District Sonoma County supervisor's seat the most expensive in county history, campaign finance reports show.

Gorin, Sawyer and independent groups reported spending $826,400, topping by $1,600 the 2010 mark set in the 2nd District supervisor's race between David Rabbitt and Pam Torliatt.

The new record marks the third time in four years that a new spending high has been reached in a county race. The trend has played out during a generational turnover on the Board of Supervisors.

The high-stakes battles for those open seats are increasingly being waged by outside groups, which operate under far fewer campaign finance restraints than candidates.

Around the state, the number of independent campaigns operating in county races has multiplied as elected officials leave term-limited higher office or lower-paying city seats for county office, experts say.

"The county supervisor gig is the best political job in California," said David McCuan, a Sonoma State University political scientist. "That's going to drive dollars to both the candidates and the outside groups."

Another contributing factor is the quick rise in the county's allowable maximum direct contribution to candidates. It has more than doubled since 2008, to a limit last year of $2,625 in any reporting period, or $5,250 in any period once independent spending reached $10,000.

Expenditures by outside groups accounted for about $219,000 of the spending in the Gorin-Sawyer race, featuring two longtime rivals on the Santa Rosa City Council.

Groups favoring Sawyer were financed primarily by real estate and business interests. They spent $142,000, mostly on advertising, according to campaign records released last week.

A coalition backing Gorin and supported primarily by the county's largest public employee labor union reported spending $77,000 on the race.

Gorin won despite Sawyer's greater campaign contributions and the deeper pockets of his independent supporters. Together the two candidates spent nearly every dollar they raised: more than $607,000. Gorin's share was about $280,000. The figures include campaign activity in 2011 and 2012.

Like many politicians, Gorin and Sawyer said they would have rather run without the influence of independent expenditures. Both cast doubt on the groups' ability to sway voters.

"A lot of people tend to tune out the robocalls and the mailers," Gorin said Friday.

But independent campaigns appear here to stay, and local politicians and their outside backers will be more aggressive in fundraising as a result, experts said.

"The saturation effect of money has gone up for all these groups," McCuan said.

The Gorin-Sawyer race did not eclipse county records for direct campaign contributions and spending, set by Rabbitt and Torliatt in their supervisorial race. Together, the two Petaluma City Council members raised more than $706,000 and spent nearly $700,000.

Torliatt, Petaluma's mayor at the time and an 18-year veteran of city politics, led the money contest. But Rabbitt, a single-term councilman, won the county seat.

(You can reach Staff Writer Brett Wilkison at 521-5295 or brett.wilkison@pressdemocrat.com.)