Donald Trump at the presidential debate. Photo: Screenshot.

Last week, Ted Cruz endorsed the man who claimed his father helped kill John F. Kennedy. And with that, the GOP cave-in is now complete. The party of Lincoln, Eisenhower and Reagan is endorsing and supporting Donald J. Trump to be president of the United States. Republican leaders have endangered America out of blind party loyalty and personal ambition. Voters cannot, and should not, forget this moment.

As the election campaign has dragged on, Trump has continually proven he is an unacceptable choice for president. He has shown autocratic tendencies, attacked groups of people based solely on race and religion, displayed extremely poor judgment, bragged about paying no income tax, used disturbing and divisive rhetoric, encouraged the use of violence against his detractors, undermined free speech, urged an American retreat from the world stage and shown that he has no core convictions or beliefs. He is a demagogue, a narcissist and a champion of strongmen and dictators. His candidacy is a betrayal of every founding principle of America.

What’s worse, the American media and our political and economic elites have simply acquiesced to the idea of a Trump presidency. They know he is unqualified, unprincipled and untrustworthy – yet treat him like a perfectly acceptable candidate. They host him on talk shows, write articles suggesting that he is on par with Mrs. Clinton and fete him at Wall Street fundraisers and political events.

Most Republicans claim they’re only supporting Trump as a bulwark against Hillary Clinton. But having worked at the highest levels of the current GOP leadership, I don’t believe that.

During my time in Washington, I saw firsthand how many Republicans in Congress were motivated solely by opposition to almost any Democrat, and by achieving power for its own sake. Opposition to President Obama often came with personal demonization, and no realistic policy alternatives. To be fair, the same can be said for many Democrats who opposed George W. Bush. But that doesn’t make it right, or justify it. Our political discourse should be held to the highest standards – not simply be a race to the bottom.

I firmly believe that Republican leaders are supporting Trump due to personal ambition and party loyalty. They know that Trump should not be president. But if he wins, they want access to power and are thus willing to support his candidacy, regardless of what it means for our country.

If it were up to me, Hillary Clinton would drop out and let someone less divisive and less tainted run for president. That would expose GOP leaders who claim to support Trump solely out of opposition to Hillary – and it might help prevent a Trump victory. But until then, Hillary Clinton is the only acceptable choice for president. A vote for anyone else (or a non-vote) is a vote for Donald Trump, and a betrayal of the American experiment.

I am not the only one who feels this way. The Dallas Morning News, which has not endorsed a Democratic candidate in 50 years, has come to the same conclusion. So have papers like the Cincinnati Enquirer and Houston Chronicle, and others will surely follow. There are also some brave Republican holdouts, like Ben Sasse and Lindsey Graham, and many public officials and thought leaders from my time in the Bush administration also oppose Trump. Between now and election day, however, it’s possible that even some of these people will take the opportunistic and partisan way out.

So what are voters and citizens like me supposed to do?

I believe it is our duty to continually and forcefully speak out against Trump. If he succeeds at subverting American democracy, it must not be with our acquiescence. We must make our voices heard, while we still can.

My proudest moment as an American used to be the three years I spent working at the White House, on behalf of our country. No longer.

I recently cast my mail-in ballot against Donald Trump. In doing so, I feel that I’ve honored the sacrifices made by our Founding Fathers, my ancestors and everyone who has given their blood, sweat, and tears to make America what it is today.