I've subscribed to Christianity Today for a long time. I was surprised by the editorial advocating Trump's removal from office, but it makes sense to me.
NZ politics is very different from American politics, for which I am profoundly grateful, but it's worth thinking about what to do in a situation where the candidate I strongly preferred on policy was thoroughly immoral. I think one of the biggest issues is the potential corrupting effect of supporting such a candidate, to my own soul and the souls of Christians around me. I think I could easily start out supporting the candidate for policy reasons while declaring their behavior detestable, but there is a great risk that over time that separation breaks down because tribalism, and a tendency to avoid cognitive dissonance, lead to defending or minimizing more and more hitherto unacceptable behavior (Isaiah 5:20). I think it's clear this happens to a lot of people. I believe that kind of personal corruption is an extremely great evil; it would be better for Christians to suffer in all kinds of ways than to fall prey to it (Matthew 16:24-26). This is all even before we consider the impact on our proclamation of the gospel message.
So a good test would be: can I resist the temptation to defend the flaws in this hypothetical flawed candidate? If not, then it is very dangerous to support them. Even if I have adequate mental discipline, there's also the question of whether they are likely to corrupt others in this way.