Reversing course from just two months ago, business leaders in Santa Clara County have abandoned plans to push for a new transportation sales tax in November to bring BART to downtown San Jose, expand Caltrain service, fill potholes and widen roads like Lawrence Expressway.

Instead the Silicon Valley Leadership Group will hold off until 2016, when voter turnout is likely to be higher during a presidential election and chances of meeting the strict two-thirds voter threshold are seen as greater.

"We're going to wait," said Carl Guardino, the Silicon Valley Leadership Group CEO who has led three successful sales tax campaigns since 1996. "Support is strong. It's just not strong enough with the suppressed voter turnout we saw on June 3 and now expect on Nov. 4."

In April, a survey showed 73 percent support for the new tax, which would raise $3.7 billion over three decades. But the latest survey saw support slip to 63 percent with a 32 percent turnout at the polls.

"This is disappointing news," said Dan Collen of the Santa Clara County roads department. "It would be nice to see something go forward this year. Pavement repairs can't wait much longer."

Randy Rentschler of the Metropolitan Transportation Commission said, "Taking the time to understand what is going on is a good thing. I don't see this as a negative issue. A lot of this is strategic."

More than a dozen transportation sales tax measures have been approved by Bay Area voters since 1976, and all but one were passed in high-turnout years involving a presidential race.

The big winner would have been BART and the Valley Transportation Authority, which needs $4 billion to tunnel under Santa Clara Street in downtown San Jose to get to Santa Clara. However, the VTA is $2 billion short, and no timetable has been set for the work until that money is in hand.

"They have to find a way to get BART fully built through San Jose," Rentschler said.

BART is now under construction in Fremont and will open in Warm Springs next year. The link to Berryessa Road along Highway 101 in San Jose will be in use by 2017.

The November election will still be of significant transportation interest to the South Bay. Alameda County remains committed to putting a half-cent tax measure on the ballot, and the polling there shows 72 percent support. That money would target the horrendous I-680 commute between the East Bay and San Jose by adding a northbound carpool lane on 680 through Fremont, putting new ramps at the 580-680 interchange and widening Highway 84.

Contact Gary Richards at 408-920-5335.