Of all the arguments against Donald Trump, the softest has been his poor prospects for victory in the general election. True, he has consistently polled worse against Hillary Clinton than have Ted Cruz, John Kasich, and virtually every other person who ran. But polls change. And if Trump were to win the Republican nomination, it would be such an earthquake that the political order might be transformed. Clinton, moreover, has huge vulnerabilities. She lacks many basic political skills, and she is a hostage to fortune—in both the usual way, as the heir to an incumbent president, and in the unusual one of being the subject of an FBI investigation.

Yet the electability argument against Trump is hardening, fast. He has a 67 percent unfavorable rating (per the Washington Post/ABC News poll), which would be the highest ever recorded for a major-party nominee, and a net favorable rating of minus-39 among white women and minus-31 among independents. Trump's numbers aren't just bad; they're the stuff of nightmares.

When you add up all of the data, there are four reasons to suspect Trump's chances in the general election are incredibly slim.

(1) The appeal of Trump was supposed to be that he would expand the electorate by bringing home white voters who didn't turn out for Mitt Romney in 2012. Looking at Trump's numbers among whites, it's not clear how he could do that—his favorability numbers are underwater not just among whites generally, but even among non-college-educated whites (where he's minus-7) and white men (minus-4).

But the Trump-wins-by-turning-out-white-Republicans theory breaks down fatally when you look at where Trump is with every other group. In order to claw his way into the poor position he's in with white voters, Trump has cheesed off every other demographic group: He's minus-53 with self-described moderates; minus-62 with voters age 18 to 34; minus-71 with Hispanics.

In order to beat Hillary Clinton, Trump has to outdo the Romney 2012 numbers. But even if he does better among white voters—and right now it looks like he'll do worse—it does no good if he can't stay at Romney's level among other groups. And Trump is poised to do much worse than Romney with just about everyone else.

(2) If this view of the general election is true, then you'd expect to see Trump's weakness showing up in general election state polling. And voilà! Three weeks ago, a poll showed Clinton leading Trump by two points in Utah. And on April 5 a poll showed Trump with a scant three-point lead over Clinton in Mississippi. In order for a Republican to win in 2016, he absolutely must win North Carolina, Florida, Ohio, Virginia, and at least a few other purplish states such as Pennsylvania, Wisconsin, Colorado, and New Hampshire.

How is Trump going to challenge in those places when he has to defend spots like Utah and Mississippi, which are supposed to be gimmes for a Republican?

(3) Trump supporters look at such numbers and argue that the general election is months and months away. But it's later than you think. We are almost exactly seven months from Election Day. Trump declared his candidacy nine months ago. We are closer to the end of this campaign than we are to the beginning.

Numbers don't move overnight. It took Trump two months to go from 5 percent in Republican polls to 30 percent. It took him seven months just to build another 10 percent of support among Republicans—the group most inclined to be open-minded about him. That shows you how hard it is for a candidate to convert marginal voters who aren't naturally part of their coalition.

And in the process of finding those 10 additional points of support, Trump alienated a great number of other voters. So even if it were theoretically possible for Trump to build a coalition to beat Clinton, everyone now knows who Trump is, everyone has an opinion about him—and he only has 30 weeks to pry people away from his would-be opponent.

(4) The Trump nomination no longer seems like a political earthquake that would realign the tectonic plates of American politics. Before Trump abandoned his quasi-nationalist populism, you could see how a Trump victory might change the Republican party and disrupt the political order in a way that could ultimately help the GOP. That view is now inoperative.

If Trump is the nominee he is either going to win it on the final day of the primaries or at a contested convention. Either way, it will be by one of the slimmest margins in history and it will signal that Trump failed to revolutionize the Republican party. Destroy the party? That's a real possibility. Take it over? Certainly. But in order to transform a party, a candidate has to offer a new program and build support among a growing number of the party's voters while also bringing the party's elites and organizational forces into the fold. Trump tried to do this initially. He has failed utterly.

Once Trump began winking about violence at the Republican convention, and his on-again, off-again capo Roger Stone started talking about helping Trump supporters visit convention delegates at their hotel rooms to "discuss" matters with them, it was clear Trump no longer had any interest in transforming the party. He wants the Republican nomination, and he is perfectly happy to brutalize the party to get it. There will be no consensus building. Only submission and capitulation. That's his prerogative, of course. Trump owes the GOP just as much as the GOP owes him—which is to say: exactly nothing.

But as an electoral matter, this change is important. Because all of the scenarios for Trump's success in November were predicated on his being capable of uniting the Republican party. And not only does he not seem capable of this task—he does not even seem interested in it.

The best reasons for opposing Trump are still the moral reasons: He is temperamentally ill-suited to the office and would endanger the republic. But the prudential reasons for opposing him are getting clearer by the day.

So clear that soon enough, even Trump's supporters may have to confront them.