LISTEN: GOP Sen. Susan Collins On Why She Can't Support Trump

Another prominent Republican is refusing to endorse Donald Trump as the GOP presidential nominee.

In an op-ed for the Washington Post on Monday, Maine Sen. Susan Collins called Trump "unworthy" of the presidency and said he does not "reflect historical Republican values."

Collins spoke with NPR's Ari Shapiro on Tuesday, expanding on her decision not to back the Republican candidate.

"It was a difficult decision for me as a lifelong Republican to decide that I could not support my party's nominee," she said. "And I kept hoping that I would see a changed Donald Trump after the primary."

She said Trump's mocking of "the vulnerable," including a reporter with a disability and a judge's Mexican heritage, contributed to her inability to support Trump's candidacy. But she said the "proverbial straw that broke the camel's back" was Trump's recent fight with the parents of a slain U.S. soldier.

"We have Donald Trump showing absolutely no empathy or compassion at all for the grieving parents of a fallen soldier and instead attacking them and attacking their religion," Collins told Shapiro.

Collins said she believes the United States is at a divisive time in history and that the country needs "someone who can help bring Americans together so that we can solve problems both here at home and abroad."

For her, that person was originally former Florida Gov. Jeb Bush.

"Unfortunately, Republican voters did not agree with me, nor with my early endorsement of him," she said of the GOP primary season.

Now, she says, she isn't sure how she'll vote. It won't be for Democratic nominee Hillary Clinton, and she could write-in a candidate. Collins said she is intrigued by the Libertarian ticket, but wishes it were reversed and that it was former Massachusetts GOP Gov. Bill Weld at the top of the ticket, instead of former New Mexico Gov. Gary Johnson.

Below are other highlights from the interview.

On Trump's temperament

"Temperament, judgment, self-restraint are essential qualities in a president. After all, we live in an extremely perilous world and Donald Trump's tendency to lash out at foes, whether they're real or imagined, could produce a very unsettling effect, in which an international event spins dangerously out of control."

On Trump and traditional GOP values

"Donald Trump does not represent traditional American values, traditional Republican values and the Republican heritage that I cherish. A fundamental Republican principle is to respect the dignity and worth of every individual and he clearly does not. He does not treat people with respect, and that is a precept we try to instill in our children, and it appears to be a lesson that has alluded him.

I don't think he is a good face for the Republican Party. I believe that most Republicans are inclusive. For example, certainly most Republicans that I know, whether in Maine or at the national level, want to see our party grow, not constrict. We believe in the big tent philosophy. We want to welcome new Americans to the Republican fold."

On how she'll vote in November

"I feel that I cannot support either party's nominee. That means that I will most likely write in my choice for president. I have taken a look at the Libertarian ticket and were the president and vice president switched, I would vote for that because I know [former] Gov. Bill Weld of Massachusetts very well, and I think very highly of him. So if he were the one running for president on the Libertarian ticket I would feel comfortable casting my vote for him. I have reservations for [former] Gov. Johnson due to what appears to be an extensive history of drug use."

On the reaction in Maine to her announcement

"By and large, it has been very favorable and I have traveled around the state a bit today. Now, there are some people who are angry with me, and I understand that and I respect their view, even though I disagree with it, that I should support the party's nominee no matter what. I've pointed out that I've always supported the party's nominee in the past, and that I will continue to work very hard for Republican candidates across the country because I believe that retaining control of the House and Senate is essential, regardless of who is elected president."

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