Republicans stand at a crossroads. With Donald Trump as the presumptive presidential nominee, we are witnessing a populist hijacking of one of the United States’ great political parties. The GOP, in putting Trump at the top of the ticket, is endorsing a brand of populism rooted in ignorance, prejudice, fear and isolationism. This troubles me deeply as a Republican, but it troubles me even more as an American. Enough is enough. It’s time to put country before party and say it together: Never Trump.

I’m not the first Republican to say Trump is a phony and should not be president, and I expect there will be many more to come. But as a former chief executive and treasury secretary, I hope to bring an additional perspective to the discussion.

Let’s start by talking about his business acumen. When Trump assures us he’ll do for the United States what he’s done for his businesses, that’s not a promise — it’s a threat. The tactics he has used in running his business wouldn’t work in running a truly successful company, let alone the most powerful nation on Earth.

Every good businessman or -woman carefully analyzes all the available facts before making a decision. Trump repeatedly, blatantly and knowingly makes up or gravely distorts facts to support his positions or create populist divisions.

He excels at scorched-earth tactics in negotiations during bankruptcy proceedings. Here, the “Art of the Deal” businessman is a master at advantaging himself over his fellow stakeholders and partners. In essence, he takes imprudent risk and, when his businesses fail, disavows his debts.