The nomination of Rex Tillerson got a boost on Sunday after two influential Republican senators — John McCain of Arizona and Lindsey Graham of South Carolina — offered tepid endorsements of the former Exxon Mobil chief. Rubio bridled at his refusal to label Russian President Vladimir Putin a "war criminal" or condemn human rights violations in Saudi Arabia and the Philippines in strong enough terms. A "no" vote from Rubio would not doom Tillerson's confirmation, because the nomination could go directly to the Senate floor without a positive committee recommendation. [...] roiling the debate is U.S.