Republican presidential candidate Gary Bauer says two of his rivals secretly want to do away with the Social Security system. During an appearance before an American Association of Retired Persons meeting in Des Moines, Bauer promised to reduce the payroll tax used to finance Social Security by 20 percent — but not allow the system to go private.Bauer said his plan would not touch “one penny” of benefits for current retirees.Bauer accused George W. Bush and Steve Forbes of playing on the fears of younger workers who believe there won’t be Social Security checks for them when they reach retirement age.Forbes wants to let younger workers keep half of the money now paid into the Social Security system so they can invest it on their own. Bush also favors privatization, but hasn’t set a figure on how much he’d reduce the payroll tax.