DALLAS — I am a Republican presidential elector, one of the 538 people asked to choose officially the president of the United States. Since the election, people have asked me to change my vote based on policy disagreements with Donald J. Trump. In some cases, they cite the popular vote difference. I do not think presidents-elect should be disqualified for policy disagreements. I do not think they should be disqualified because they won the Electoral College instead of the popular vote. However, now I am asked to cast a vote on Dec. 19 for someone who shows daily he is not qualified for the office.

Fifteen years ago, as a firefighter, I was part of the response to the Sept. 11 attacks against our nation. That attack and this year’s election may seem unrelated, but for me the relationship becomes clearer every day.

George W. Bush is an imperfect man, but he led us through the tragic days following the attacks. His leadership showed that America was a great nation. That was also the last time I remember the nation united. I watch Mr. Trump fail to unite America and drive a wedge between us.

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.