washington head u.s. senate judiciary committee ask fbi whether warn donald trump presidential campaign allege attempt russia infiltrate campaign republican senator chuck grassley office say thursday write federal bureau investigation director christopher wray ask whether agency provide defensive brief trump team give ongoing investigation paul manafort trump campaign manager fbi provide defensive brief similar warn campaign would raise important question trump campaign respond grassley write letter date sept. 20. fbi alert campaign grassley say would raise serious question factor contribute decision appear handle differently similar circumstance involve previous campaign senator say accord press report u.s. intelligence raise similar concern john mccain republican senator 2008 presidential campaign grassley however ask fbi possibility offer trump campaign officials brief offer decline 2016 election two u.s. intelligence officer fly new york brief president-elect trump russia find arrive trump tower brief cancel two senior u.s. officials say speak condition anonymity manafort become trump campaign manager june 2016 force resign two months late amid report business relationship kremlin-backed former ukrainian leader viktor yanukovich trump deny campaign collude russia dismiss investigations allegations russian interference election witch hunt russia deny meddle u.s. election senator ask fbi warn trump campaign russian meddle