A campaign to oppose three proposed City Charter amendments backed by the local firefighters union began Thursday with the forming of a political action committee expected to raise “well north of half a million dollars.” The PAC, called San Antonians for Fiscal Discipline, was set up soon after City Clerk Leticia Vacek told the City Council that the San Antonio Professional Firefighters Association had collected enough valid signatures on its petitions to force a charter-amendment election. The firefighters union, led by president Chris Steele, launched a campaign in February to gather the 20,000 required signatures on each petition to force a charter-amendment election. In an interview Thursday afternoon, he said “it doesn’t matter how much money the opposition puts out. The issues speak for themselves.”