A measure to expand Alameda County’s sales tax for transit is drawing support from environmental groups and unions, as well as chambers of commerce and even an anti-tax group. The support marks a big change from the last attempt to extend the county transit tax in 2012, when environmentalists and advocates for poor and disabled transit users with-held their support, largely because they wanted more support for bus service. That measure narrowly failed at the ballot. The new version of the tax measure includes more funding for mass transit, as well as bus passes for youths and seniors. Christopher Martinez reports from Oakland.