Democratic presidential hopeful Bill Bradley attacked corporate pork yesterday, announcing that as president he would work to eliminate tax shelters, loopholes, and subsidies that favor big companies, including those engaged in environmentally destructive practices. Bradley specifically said he wants to cut benefits to mining companies that drill on public land and pay small royalties, oil and gas producers that get deductions for exploration and development costs, and ranchers who graze livestock on public land — changes estimated to save $2 billion over a decade. Bradley’s plan would also revive the Superfund tax on chemical companies, which expired in 1995 after Senate Republicans blocked an extension. Bradley said he won’t be going after the ethanol subsidy, which has big boosters among farmers in Iowa, site of the nation’s first caucus, as well as support from enviros.