Supervisor Mike Wasserman, a Los Gatos resident and former mayor and council member, cast the dissenting vote.
"I feel our local taxes are already among the highest in the state and the cost of living here is already very high," Wasserman said about his opposition to the measure.
A secondary approval to the measure would be needed at a meeting on Aug. 7 before it could go on the ballot, according to Supervisor Ken Yeager's office.
If county supes have their way, local residents will see the sales tax go up once again from 8.375 percent to 8.5 percent.
"We, at the County, particularly the employees, have cut and sacrificed much creating a much leaner operation now," said Supervisor Dave Cortese who's supporting the measure.
Cortese said the 1/8-cent sales tax will allow the county to be more sustainable in the next 10 years. The revenue is needed to give Santa Clara Valley Medical Center about $50 million to operate annually. "We never want to be in a position to have to shut down an emergency room or deny people care," Cortese said. "An eighth-cent is reasonable to ask people to make that contribution over 10 years ... given what we've done to rein in spending."
The funds generated by the tax increase would be used for a variety of countywide services, including public safety, health programs for low-income children, housing for the homeless, and programs aimed at helping students stay in school.
Since being elected in 2008 to the Board of Supervisors, Cortese said the body has made three-quarters of a million in reductions, with county employees giving $75 million in recurring wage concessions. "We've asked everyone to do everything they can internally and now it's just a matter of the last piece of the puzzle to ask taxpayers to invest an eighth cent and put our programs on real firm footing for the next 10 years."
If the tax increase is allowed by voters, revenues collected would total an estimated $500 million over 10 years, according to a statement issued by the county. The tax would go into effect April 1, 2013, and sunset in 10 years.
Wasserman said the tax will make it harder for businesses and individuals to continue to conduct commerce in the county. He noted when combined with the tax measures in the November ballot, the potential cumulative increase in taxes for local residents "is downright scary."
"I just don't think that's the way to right the ship either city, county, state," Wasserman said.
Wednesday's vote took place at a 4 p.m. special meeting in the Board of Supervisors chambers at 70 W. Hedding St. in San Jose.
—Bay City News Service contributed to this report