moscow russian lawyer meet donald trump jr. father republican nomination 2016 u.s. presidential election say ready testify u.s. congress dispel call mass hysteria encounter president donald trump eldest son eagerly agree june 2016 meet natalia veselnitskaya woman tell russian government lawyer might damage information democratic white house rival hillary clinton accord email release trump jr. veselnitskaya previously say private lawyer never obtain damage information clinton tie kremlin ready clarify situation behind mass hysteria lawyers testify senate veselnitskaya say interview russia kremlin-backed rt tv channel release late tuesday washington wednesday u.s. senator dianne feinstein top democrat senate judiciary committee tell reporters aware veselnitskaya offer feinstein say yet discuss call veselnitskaya testify committee chairman chuck grassley republican russian officials repeatedly deny allegations u.s. intelligence agencies moscow interfere presidential campaign help trump win white house trump deny collusion campaign russia leaders u.s. senate intelligence committee say want speak everyone attend meet part investigation russia u.s. election russian lawyer meet trump jr. say ready testify congress