Gov. Jerry Brown signed a bill Wednesday that permits Alameda and Contra Costa counties to seek voter approval to raise their county sales tax for transportation

It's unclear when the counties would seek a tax increase. Without the legislation, however, neither county could seek an increase, which would exceed a state cap on the local sales tax in some cities in the two counties.

Now both county's transportation commissions can opt to go to the ballot by Dec. 3, 2020, under AB 210, authored by Assemblyman Bob Wieckowski, D-Fremont.

Last November, Alameda County voters narrowly failed to pass a transportation sales tax increase from a half cent to one cent. The measure needed two-thirds support at the polls, but got 66.53 percent.

Contra Costa County leaders have discussed the possibility of seeking an increase in their half-cent sales tax after they revamp a long-term plan for transportation projects.

"Gov. Brown recognizes the need to invest in our infrastructure and I'm sure he appreciates the fact that none of these projects will go forward without the support of local voters," Wieckowski said in a written release.

Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff