WASHINGTON, May 13 -- Americans for Tax Reform posted the following commentary: * * * Charles McCall Signs No-Tax Hike Pledge in Race for Governor, Looks to Build on Tax-Cutting Record Americans for Tax Reform commends former Oklahoma House Speaker Charles McCall for signing the Taxpayer Protection Pledge in his campaign for governor. By signing the pledge, McCall has made the strongest public commitment to Oklahoma voters that he will oppose any and all tax hikes as governor. Candidates of  more