washington president barack obama issue scathing attack donald trump tuesday criticize muslim family whose u.s. army captain son kill iraq challenge republican leaders withdraw support unfit nominee obama comment add grow number statements republicans democrats lambast trump criticism khizr ghazala khan appear democratic national convention last week trump question whether mrs. khan speak convention prevent religion characterize mr. khan criticism vicious families lose sons daughters serve u.s. military call gold star families notion would attack gold star family make extraordinary sacrifice behalf country fact appear basic knowledge around critical issue europe middle east asia mean woefully unprepared job obama say trump white house news conference democratic president note lead republicans include speaker house representatives paul ryan senate republican leader mitch mcconnell one-time republican presidential nominee john mccain u.s. senator arizona criticize trump remark stand endorsements question think ask repeatedly say strong term say unacceptable still endorse obama say say party standard-bearer obama say obama speak white house news conference singapore prime minister lee hsien loong obama endorse former secretary state hillary clinton democratic nominee president obama say even lose white house race 2008 mccain 2012 former massachusetts governor mitt romney would doubt abilities lead country case trump businessman new york obama say come point say somebody make kinds statements judgment temperament understand occupy powerful position world obama say obama republican leaders still endorse trump