GOP Senator: Here's Why I Can't Support Trump 50 GOP security officials sign letter against Trump By Rob Quinn, Newser Staff Posted Aug 9, 2016 12:45 AM CDT Updated Aug 9, 2016 5:33 AM CDT 254 comments Comments Sen. Susan Collins says she won't be voting for Trump. (AP Photo/Evan Vucci) (Newser) – Another Republican senator has shifted from "undecided" to "definitely not voting for Donald Trump." In a Washington Post op-ed, Maine Sen. Susan Collins writes that she has concluded that Trump does not "reflect historical Republican values nor the inclusive approach to governing that is critical to healing the divisions in our country." She says three incidents convinced her that Trump "lacks the temperament, self-discipline, and judgment" to be president: His mocking of a disabled reporter, his insistence that federal judge Gonzalo Curiel's Mexican heritage made him biased, and his "inconceivable" criticism of the Khans, after which Trump once again "proved incapable of apologizing, of saying he was wrong." Collins writes that she had hoped Trump would tone it down after the convention, but she has realized that "regrettably, his essential character appears to be fixed, and he seems incapable of change or growth." Earlier Monday, 50 senior Republican national security officials from several administrations, including former CIA director Michael Hayden, signed an open letter declaring that they will not be voting for Trump, the New York Times reports. Trump "lacks the character, values, and experience" to be president, they wrote, warning that he would be "the most reckless president in American history." "The names on this letter are the ones the American people should look to for answers on why the world is a mess," Trump fired back in a statement condemning the letter.