evidence: Two other GOP senators remain undecided — Utah's Mitt Romney and Alaska's Lisa Murkowski. Both indicated they wouldn't announce their decisions until Friday morning, although Romney's office said late Thursday that he's said "repeatedly" he wants to hear from former National Security Adviser John Bolton and "thus will vote for the motion tomorrow." Four GOP senators would have to join all the Democrats to ensure the testimony of witnesses. Even if both Murkowski and Romney were to vote in favor of calling witnesses, it would likely result in a 50-50 stalemate. [...] Romney's office told CBS News the senator has said "repeatedly" he wants to hear from Bolton and "thus will vote for the motion tomorrow."