Sen. Susan Collins said Tuesday she'd had her doubts about Donald Trump, but it was his attacks on Gold Star parents Khizr and Ghazala Khan, that became the "tipping point" that made her decide she would not vote for the GOP nominee.
"These are the parents who lost their son in the war, when he showed absolutely no empathy or compassion for their terrible loss," the Maine senior Republican senator told CNN's Jamie Gangel in an exclusive interview.
"Instead, [he] attacked these two Gold Star parents and also attacked their religion. That was just the final straw for me."
Trump's attacks on the parents, whose son Capt. Humayun Khan was killed in an explosion, came after Khizr Khan spoke out strongly against Trump, while his wife stood silently by, during the Democratic National Convention. In Trump's first comments on the speech, he questioned why Khan's wife did not speak, and speculated it was because she was not allowed to comment.
This lead the Khans to speak out against Trump in several interviews.
Collins told Gangel that she also opposes Trump because she thinks he would "make a perilous world even more dangerous," echoing comments she made in a Monday opinion piece for The Washington Post.
"I worry that his tendency to lash out and his ill-informed comments would cause dangerous events to escalate and possibly spin out of control at a time when our world is beset with conflicts," she told Gangel. "That is a real problem."
She also said she will not support Clinton, as she is concerned that her policies could damage the United States economically. Further, Collins said she is concerned about Clinton's use of a private email server while she was secretary of state.
She's said she's also not quite ready to vote for Libertarian nominee Gary Johnson, although she said if the ticket were turned and Johnson's running mate, Bill Weld, was on top, she'd vote for him.
"I do not know Gary Johnson," said Collins. "I'm concerned about some of his views on drug use, and I will have to take a hard look at that. I may well end up writing in a name for president."
She also denied that a letter written and signed by 50 key GOP national security experts against Trump played into her decision, even though she's served on the Senate Intelligence Committee and chaired the Senate Committee on Homeland Security from 2003-2007.
"I certainly respect and worked closely with many of the 50 intelligence, defense and Homeland Security officials who signed that letter," said Collins, "but my decision was my own."
She explained her decision "certainly was informed" by her years chairing Homeland Security and by the regular briefings she receives on the Intelligence Committee, and said it was difficult to decide that she "just cannot support Donald Trump."
"I do not believe that he is the president that we need at this time in our country's history and I believe that in many ways he is antithetical to the values of the Republican Party," she said.
"The Republican Party believes in the dignity and worth of the individual. Based on what I've seen Donald Trump say over and over and over again, that is not his style. "