new york former fbi director jam comey testimony u.s. president donald trump expect loyalty hop comey would drop investigation former top aide could bolster obstruction justice allegations trump several legal experts say allegations might use basis impeachment proceed analysts say step would face steep hurdle however would require approval u.s. house representatives control trump fellow republicans accord write testimony post senate intelligence committee website wednesday comey say trump tell one-on-one feb. 14 conversation former national security adviser michael flynn good guy hop comey could see way clear let go probe tie flynn russia trump fire flynn previous day controversy contact retire general russian ambassador unite state comey account release ahead appearance committee thursday could show trump intend impede flynn investigation say michael gerhardt professor constitutional law university north carolina school law express discussion loyalty disconcert could heighten speculation president try exert pressure least exert influence russia investigation gerhardt say comey fire trump may lead fbi investigation flynn look allegations link russia trump 2016 presidential campaign moscow trump deny collusion trump lawyer marc kasowitz immediately respond reuters query whether comey testimony would support obstruction case say statement trump felt vindicate comey confirmation investigation russia probe build criminal obstruction justice case federal law require prosecutors show person act corrupt intent matter whether person succeed impede investigation sit president unlikely face criminal prosecution obstruction justice could form basis impeachment bruce green professor fordham university school law say would difficult show trump intend impede flynn investigation say trump could say merely vouch flynn character voice concern probe interfere ability function president alan dershowitz professor emeritus harvard law school well-known defense lawyer add trump comment comey ambiguous statements even close obstruction justice legal experts say however detail surround feb. 14 conversation could indicate trump intend interfere flynn probe accord comey trump tell close advisers include attorney general jeff sessions jar kushner leave room could speak comey privately ask others leave room could suggest president aware something wrong say andrew wright professor constitutional law savannah law school wright say damage detail comey testimony include comey document conversations former president barack obama felt compel first conversation trump comey testimony maximum damage trump wright say gerhardt agree testimony blow trump say people concern concern now comey account could fuel obstruction accusations trump legal experts