Social Security Institute President Larry Hunter, a longtime Republican adviser, will launch the for-profit Alliance for Retirement Prosperity on Wednesday, representing a $5 million conservative challenge to the AARP. Where the nonpartisan, nonprofit AARP has sided with the Obama administration on many issues — most recently and most prominently, ardently supporting the health care reform law — the alliance will actively lobby for the law's repeal. Among its top-ticket agenda items: "Repeal ObamaCare, prevent the rationing of health care and reform Medicare and Medicaid." Other conservative groups, such as the 60 Plus Association and the American Seniors Association, have also...