washington republican presidential candidate donald trump cast doubt nation economic health say tuesday u.s. economy bubble fear burst want deal financial collapse elect white house billionaire real estate mogul cite economy one tough assignments would face president win nov. presidential election along iran nuclear deal daunt task deep trouble country mess trump tell abc good morning america program bubble add trump front-runner republican presidential nomination frankly go bubble pop hope pop become president want inherit stuff rather day rather day tell that recent u.s. job growth strong late government data show nation unemployment rate hold steady last month 7-1/2-year low percent even people enter labor force sign confidence job market u.s. economy grow percent annual pace manufacture industrial sectors show weakness slump oil price slow growth china cast pall outlook global economy world market slump amid worry china debt look stock market today look last week trump say ... go much november trump accuse u.s. federal reserve keep interest rat low help democratic president barack obama say high rat would burst u.s. economic bubble obama take office january 2009 amid big u.s. financial crisis decades lead bank auto industry bailouts multibillion-dollar economic stimulus package report washington newsroom edit dunham sap sponsor coverage independently produce staff reuters news agency trump say u.s. economy 'bubble n't want inherit