A Republican member of the Electoral College from Texas has said he will not be casting one of his state's 38 electoral votes for President-elect Donald Trump.
If Christopher Suprun goes through with his plan on December 19, it would make him the first "faithless elector" since 2004.
But, in an opinion piece for the New York Times, Suprun says Trump shows "daily he is not qualified for the office".
"I watch Mr. Trump fail to unite America and drive a wedge between us," Suprun writes. "Mr. Trump goes out of his way to attack the cast of "Saturday Night Live" for bias.
"He tweets day and night, but waited two days to offer sympathy to the Ohio State community after an attack there. He does not encourage civil discourse, but chooses to stoke fear and create outrage.
"This is unacceptable. For me, America is that shining city on a hill that Ronald Reagan envisioned. It has problems. It has challenges. These can be met and overcome just as our nation overcame Sept. 11."
Explaining his reasons for not voting for Trump, Suprun, an ex-firefighter who was part of the response to the 9/11 attacks, also writes that he believes Trump lacks the "foreign policy experience to serve as commander in chief".
He says he takes issue with the advisers Trump has surrounded himself with, such as Gen Michael T Flynn, who he has picked as his national security adviser, and who has "installed a secret internet connection in his Pentagon office despite rules to the contrary".
"The election of the next president is not yet a done deal," writes Suprun. "Electors of conscience can still do the right thing for the good of the country.
"Presidential electors have the legal right and a constitutional duty to vote their conscience."
He ends the article by saying: "Fifteen years ago, I swore an oath to defend my country and Constitution against all enemies, foreign and domestic. On Dec. 19, I will do it again."