When it comes to political predictions, Karl Rove may not have the unblemished record of incompetence compiled over the years by Bill Kristol, the man with the grin of the Cheshire Cat and the cutting insight of the Mad Hatter.

However, when Rove has been wrong, he has been wrong in dramatic and highly entertaining fashion.

There was the time before the 2006 midterms, when Rove haughtily told an NPR interviewer that while others might cite math and polling numbers, only Rove possessed "THE math," and "THE math" told him that the Republicans were a lock to hold onto both the House and Senate.

A few days later, they lost both the House and Senate.

And of course, there was that delicious moment late on Election Night 2012, when a distraught Rove kept insisting that Mitt Romney was going to win Ohio and thus the presidency, even though the number crunchers at Fox News had already called the state and election for Barack Obama. Rove's impassioned protests notwithstanding, Obama ended up winning the state by a comfortable margin of almost three percentage points.

Given all that, I get a little fearful when Rove predicts that "If Mr. Trump is its standard-bearer, the GOP will lose the White House and the Senate, and its majority in the House will fall dramatically." While I too think that's true, I worry a little when I find that both Rove and Kristol agree with me. So let me double-check my logic and my facts:

First, let's set the baseline. Even before Trump rose to such dominance, I thought it unlikely that the GOP would hold the Senate this year. They have 24 seats to defend this cycle, several in Democrat-friendly states. The Democrats defend only 10 seats, all of them considered safe.

In fact, under the circumstances I shake my head in bafflement at the GOP's refusal to even consider a Obama nominee to the Supreme Court. That nominee is likely to be exceedingly moderate and non-controversial, perhaps even someone that the Senate has previously confirmed for a judgeship with unanimous Republican support. That reflects the fact that the Republicans do have some leverage at the moment.

However, political markets give the Republicans just a 39 percent chance of retaking the White House. And if the Democrats hold the White House and take the Senate, Republicans may face a Supreme Court nominee of an entirely different sort come January, when they won't have the political power to influence or stop it. By taking this position, they are gambling with their hearts not their heads, and from desperation rather than from strength.

They've also put senators such as Kelly Ayotte of New Hampshire in a bind. Her seat is critical to GOP hopes of holding onto the Senate, and if she hopes to win in a state that Obama carried by 5.5 percentage points in 2012, she has to sell herself to her voters as a moderate willing to compromise. That's tough to do after announcing that she will refuse to even meet with Obama's judicial nominee, the most basic of political courtesies.

Now, toss in Trump as the party's standard-bearer, and the prospect grows significantly worse.

Trump supporters will argue that the man has brought new energy and new voters to the process, and that does appear to be true. GOP turnout in primaries and caucuses is extremely high, and Trump is almost certainly the inspiration for that. You could also make the case that his anti-trade, pro-jobs rhetoric -- as empty as it is -- could pull votes from traditional Democratic groups in parts of the country that have been devastated by the movement of industry overseas.

We're also witnessing an effort by Republicans to bargain with the near-inevitable and convince each other that hey, maybe a Trump win won't be so bad! For example, GOP Chair Reince Priebus is now claiming that if Trump does win the nomination, the GOP establishment will have "leverage" over him and be able to moderate his behavior because the newly anointed nominee will want access to the party's expertise, data and financial resources.

I'm not buying it, and I'm sure the statement made The Donald break out in a yuge grin.

The truth is that having Donald Trump as its nominee would devastate the Grand Old Party. It would march into the general election deeply, profoundly confused about its identity, its future and its ideology, with many conservatives reluctant or outright refusing to be associated with Trump's outlandish rhetoric.

Look at what's happening already, before the nomination is even clinched. Republicans who a few months ago demanded that Trump promise not to launch a third-party campaign should he lose the nomination are now muttering about a third-party effort of their own in case he wins. A month ago, Erick Erickson was still saying that he would vote for Trump over Clinton. Today he says "I will not vote for Trump ... ever," and is offering up Rick Perry as a third-party option.

"Couldn't vote for Trump, couldn't vote for Hillary," says Kristol, who long ago endorsed the third-party option to Trump, in his case choosing Dick Cheney as the option. Ron Paul also says that he could not vote for Trump in November.

“It would be an utter, complete and total disaster,” says Sen. Lindsey Graham. “If you’re a xenophobic, race-baiting, religious bigot, you’re going to have a hard time being president of the United States, and you’re going to do irreparable damage to the party.”

"I know that I won't go to the polls," says Glenn Beck, who has taken to dark mutterings about Trump and his "Brownshirts."  "I won't vote for Hillary Clinton and I won't vote for Donald Trump. I just won't. And I know a lot of people that feel that way."

Writing in The Federalist, conservative David Harsanyi warns that Trump poses a far greater danger to the country and to the conservative movement than Hillary ever could, implying that she is the better choice:

"You can't let a mob run your party. And it's not a mob because it's hyper-populist or constructed around a cult of celebrity or even because it's angry — though all those things are true. The problem is that it's incoherent and nihilistic."

I think that word "nihilistic" is accurate and important. Trump's supporters have to sense that their crusade against the party establishment has a very high probability of wrecking the GOP as we have known it.  For many, that isn't merely a risk that they're willing to accept. That's the point of the whole exercise. Their excitement over Trump is motivated not by what he promises to build, but what he promises to destroy.

The idea that a party struggling with all that can somehow unite itself behind a Trump and be victorious in November simply is not rational. Yes, he'll pull a number of first-time voters to the polls, and a number of Democrats as well. But many more conservative-leaning voters will just stay home, with potential ramifications far down the ballot.