Roger Katz, a former Republican state senator and co-chair of Maine Republicans for Harris, chats with Democratic National Committee Chair Jaime Harrison after Harrison stopped by a kickoff Harris campaign canvassing effort in Brunswick in August. Brianna Soukup/Press Herald

An open letter to my four grandchildren:

I want you to understand someday why your grandfather, a lifelong Republican, is voting for Kamala Harris for president.

My first political memory is being 6 years old and riding with your great-grandfather in a Gardiner parade for Dwight Eisenhower way back in 1956. I still have the campaign button from that day. Remind me to show it to you.

Your great-grandfather Bennett was a role model of what a moderate Republican should be. Since I was old enough to vote, I identified with that party and usually voted that way because of my alignment with the GOP’s principles of respect for the rule of law, fiscal, responsibility, limited government, and (at least years ago) respect for women’s rights to make decisions for themselves.

Those principles began eroding during the Tea Party era, but were completely swept away beginning in 2016. Before then, I cannot ever recall a single candidate from either party whose singular mission was to divide our nation and place us at war with one another over race, ethnicity, and gender. Donald Trump changed all that. Inexplicably, most of the GOP has followed him down that dark road. The “big tent party” I knew was gone, replaced by allegiance to a charlatan. That party is now largely unrecognizable to me.

There are many Biden and Harris policies I disagree with. But that is not the point. Let’s have a vigorous debate about how to improve our economy, the size of our national government, mitigating climate change, and the best path forward to curb gun violence. But this time, all those other issues sadly do not matter very much.

The overriding reality which dwarfs everything else is this: Donald Trump is a threat to our very democracy. Against all evidence, he still insists he won the last election. Like the Wicked Witch of the West sending out the flying monkeys in “The Wizard of Oz,” he dispatched the mob to the Capitol on Jan. 6, trying to sabotage the peaceful transition of power for the first time in our nation’s history.

If elected again, he promises to convene military tribunals to punish his political enemies,  “terminate” the constitution if that serves his purposes, and pardon the thugs (he calls them “hostages“) who were convicted for assaulting the police on Jan. 6. He mocks military heroes like John McCain while openly sucking up to Vladimir Putin. This is a man who openly talks about setting up what can only be described as concentration camps to house millions of immigrants, a suggestion eerily reminiscent of Germany in the 1930s.  We know how that turned out.

And oh, yes, he is a now a convicted felon.

Many of the people who know him best fear him the most. Several he himself appointed — a chief of staff, a secretary of state, a head of the joint military chiefs, and an attorney general, all of whom had a front row seat to the dysfunction and chaos — have bravely told us he is unfit to serve.

Your grandfather is one of a growing number Republicans who want our party to get back to its roots. Republicans for Harris started as a trickle, then became a stream, and is now almost a raging river. If enough other Republicans join us in saying “not this time,” we can put this dangerous and flawed man behind us and try to rebuild the party.

There is no political risk to me — my days in elected office are behind me. But others have lost their careers for speaking out. Geoff Duncan is the former Republican lieutenant governor of the red state of Georgia who bravely did not hesitate to put country over party. His message from the Democratic convention to Republicans was simple: “Let me be clear to my Republican friends at home watching: If you vote for Kamala Harris in 2024, you’re not a Democrat. You’re a patriot.” Amen to that.

I am being selfish in writing this. I want you four grandkids to grow up in a country where people respect the law, believe in the peaceful transition of power, honor our military, keep the government out of women’s health decisions, and appreciate our nation’s obligation to be a force for good in the world.

If Donald Trump gets elected, I am afraid that all may be in jeopardy now.