Donors, analysts and media are naturally drawn to the horse-race aspect of politics: establishment vs. anti-establishment, insider vs. outsider. But Trump is proposing a massive ideological and moral revision of the Republican Party. Re-created in his image, it would be the anti-immigrant party; the party that blows up the global trading order; the party that undermines the principle of religious liberty; the party that encourages an ethnic basis for American identity and gives strength and momentum to prejudice.

We are already seeing the disturbing normalization of policies and arguments that recently seemed unacceptable, even unsayable. Trump proposes the forced expulsion of 11 million people, or a ban on Muslim immigration, and there are a few days of outrage from responsible Republican leaders. But the proposals still lie on the table, eventually seeming regular and acceptable.

But they are not acceptable. They are not normal. They are extreme, and obscene and immoral. The Republican nominee -- for the sake of his party and his conscience -- must draw these boundaries clearly.

Ted Cruz is particularly ill-equipped to play this role. He is actually more of a demagogue than an ideologue. So he has changed his views on immigration to compete with Trump -- and raised the ante by promising that none of the deported 11 million will ever be allowed back in the country. Instead of demonstrating the humane instincts of his Christian faith -- a faith that motivated abolition and the struggle for civil rights -- Cruz is presenting the crueler version of a pipe dream.

For Republicans, the only good outcome of Trump vs. Cruz is for both to lose. The future of the party as the carrier of a humane, inclusive conservatism now depends on some viable choice beyond them.