Sen. Susan Collins, R-Maine, said Tuesday she'll probably write in a name for president this Nov. 8, something the lifelong Republican said she has never done before.

Collins' remarks come not long after she announced earlier this week in an op-ed published by the Washington Post that she refuses to vote for GOP nominee Donald Trump.

"He simply does not have the restraint and the consideration and the judgment and the knowledge to handle those dangerous events, with which presidents are inevitably confronted," Collins said Tuesday in an interview with CNN.

The Maine lawmaker said her decision has been informed by other Republicans who've distanced themselves from the party's nominee, but stressed her decision "was my own."

"It certainly was informed by the many years that I served as the chairman of the Senate Homeland Security, as well as the regular briefings that I receive now as a member of the intelligence committee," she said, echoing widespread concerns that Trump poses a threat to national security.

"But the conclusion that I drew was based more on my own experience than listening to those experts, much as I respect them," she added.

And as for whom she will vote for in November: The senator said she has no idea.

"I truly don't know. I have a lot of concerns about Hillary Clinton, and I am not going to support her. If the Libertarian ticket were reversed with Gov. Bill Weld, former governor of Massachusetts, leading that ticket, then I would vote for the Libertarian ticket, because I know Bill Weld well and I respect him a great deal," she said. "I do not know Gary Johnson. 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, something I've never done before."

For the senator, writing in someone's name on Nov. 8 would be a first.

"I have always supported my party's nominee. That's what made this decision so difficult. But in the end, I 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's antithetical to the values of the Republican Party," Collins said.

"The Republican Party believes in the dignity and worth of the individual," she added. "I've seen Donald Trump … that is not his style.

On Monday, Collins explained her opposition to Trump has a lot to do with his attacks on people who do not have platforms with which they can respond.

These attacks specifically, she concluded, have revealed Trump is "unworthy of being our president."

"My conclusion about Mr. Trump's unsuitability for office is based on his disregard for the precept of treating others with respect, an idea that should transcend politics," the senator wrote.

"Instead, he opts to mock the vulnerable and inflame prejudices by attacking ethnic and religious minorities," she added.

The worst examples of such behavior, she explained, are Trump's attacks on a reporter with disabilities, his ongoing fight with Judge Gonzalo Curiel and the GOP nominee's back-and-forth with a Gold Star family of Muslim faith.