House Intelligence Chair Adam Schiff (D-Calif.) criticized Republicans for not speaking out against President Trump's commutation of Roger Stone's prison sentence, pointing out on ABC's "This Week" that Stone was convicted for lying to a GOP-led committee.The big picture: Sens. Mitt Romney (R-Utah) and Pat Toomey (R-Penn.) are the only Republican senators who have condemned the move, with Romney calling it "unprecedented, historic corruption" and Toomey noting that Stone was "duly convicted" by a jury.Trump lashed out at both senators on Twitter late Saturday night, calling them RINOs (Republicans In Name Only) and accusing former FBI officials of spying on his campaign.Schiff claimed Trump has "abused the pardon power" to protect himself from "criminal liability," which he said is an impeachable offense. But he added: "If the Republicans won't even say a word, of course they're not going to vote to impeach and convict."What he's saying: "Republicans won't stand up for the rule of law, won't stand up for the independence of the Justice Department. It shouldn't matter, but this was a Republican-led investigation that Roger Stone lied to," Schiff said."The committee was then chaired by a Republican, and here you have no more than a couple Republicans willing to say a single word about someone who came before Congress and lied to them, intimidated witnesses and obstructed them. Why? Because he did it to cover for a president of their party.""This is the distinction between now and Watergate. The Republicans then would not have stood for this, and Nixon understood that. Donald Trump understands that he has these Republicans cowed."Go deeper: Robert Mueller speaks out on Roger Stone commutation