SAN ANTONIO – A former rival of Mayor Ron Nirenberg says he is stepping up to rally opposition against two San Antonio sales tax proposals on the November ballot. He also denied that wading into the sales tax fight is a way to set up another campaign to challenge Nirenberg in 2021, though he believes his mayoral campaign resonated with voters. The proposals he’s opposing, championed by Nirenberg and VIA Metropolitan Transit officials, revolve around new uses for a 1/8 cent portion sales tax. Since the proposals would use the same portion of the sales tax at different times, there would be no change to the 8.25% sales tax rate San Antonio shoppers currently pay -- something to which Nirenberg and VIA officials have repeatedly pointed. The campaigns supporting both sales tax measures provided reactions to Brockhouse’s plans to rally opposition.