washington eight republican candidates qualify prime-time fox news/google debate thursday donald trump win center-stage spot top-polling candidate fox news announce tuesday trump say tuesday likely attend debate last one iowa caucus monday mark first contest nomination race nov. presidential election trump engage public spat fox news begin debate last august say subject unfair question moderator megyn kelly let see much money fox make without debate trump tell news conference marshalltown iowa senator rand paul kentucky fail qualify main event last debate make cut time participants p.m. est debate texas senator ted cruz florida senator marco rubio retire neurosurgeon ben carson new jersey governor chris christie former florida governor jeb bush ohio governor john kasich former hewlett-packard chief executive carly fiorina former arkansas governor mike huckabee former pennsylvania senator rick santorum former virginia governor jim gilmore qualify p.m. est debate low-polling candidates fail qualify prime-time debate hold early month paul decline participate so-called undercard debate report eric beech edit eric walsh sap sponsor coverage independently produce staff reuters news agency eight republican candidates qualify thursday 's debate trump uncertain