If the average of recent polls showing Donald Trump losing to Hillary Clinton by more than 11 percentage points is correct, you’d have to go back to Ulysses Grant’s 1872 thumping of Horace Greeley to find such a landslide.

Even recent elections that we think of as utter domination (1980 – Ronald Reagan over Jimmy Carter by 9.7%, 1988 – George H.W. Bush over Michael Dukakis by 7.7%, 1996 – Bill Clinton over Bob Dole by 8.5%, 2008 – Barack Obama over John McCain by 7.3%) pale in comparison to Trump’s looming loss to Clinton.

Perhaps the comparison to 1872 is particularly apt as Grant, running for re-election, carried a whiff of corruption and scandal (which turned into outright stench a few years later) but won an overwhelming victory against a famous but unappealing challenger who ran, literally, as a Liberal Republican. In 2016, we face the spectacle of an utterly corrupt, national-security-risking, professionally incompetent Alinsky-loving rape-defending shakedown artist and liar trouncing the current front-runner of the FGOP (Formerly Grand Old Party) who has a lifetime full of holding liberal policy positions.

From time to time, “conservatives” tell me that my consideration of electability — who has the best chance of winning the general election — is misplaced and I should focus more on principle. Then when I do (as I always do anyway), and write that, for example, I can’t support John McCain, they tell me that the most important thing is beating the Democrat and I should vote for any candidate, no matter how flawed, who has an “R” after his name. They can’t have it both ways.

Some of those same people, whether pundits or activists or readers of these pages, are today supporters of Donald J. Trump. It would be one thing if Mr. Trump were either conservative or electable. But in fact he is neither.

There is almost nothing more important in 2016 than defeating Hillary Rodham Clinton in the November elections. Mrs. Clinton is a power-mad radical without a principled bone in her body who earns millions by peddling influence to cronies and foreign governments. And that’s the nicest thing I can think to say of her.

But those who claim that Donald Trump will redraw the electoral map, leading to a victory that no other Republican could achieve, are engaged in what Mrs. Clinton might call a “willing suspension of disbelief.”

In short, the idea that Donald Trump can beat Hillary Clinton in November is sheer fantasy.

A few data points to consider:

• The most recent CNN/ORC poll of the 2016 election shows that a stunning 67 percent of registered voters have an unfavorable opinion of Mr. Trump, far more than even the appalling Hillary Clinton who stands at 56 percent unfavorable. Back when Trump’s unfavorability rating was a mere 60 percent, Gallup reported that that made Trump the least favorably viewed presidential candidate since they began tracking this question in 1992.
• In the same poll, Clinton and Trump are tied (at 45 percent) on the question of which candidate is “a strong and decisive leader,” a very weak performance for a man whose entire candidacy is based on that precise trait.
• On every other question of key presidential characteristics and qualities, including being “in touch with problems facing the middle class,” able to “handle the responsibilities of commander in chief,” “more honest and trustworthy,” and “a person you admire” Mrs. Clinton crushes Mr. Trump by an average of 11 points. Yes, Donald Trump is losing to Hillary Clinton on honesty and admirability. And this isn’t the only poll to show the same result.
• According to RealClearPolitics, Trump has led Clinton in only 5 of 55 polls taken since last May, with Clinton’s lead widening substantially over the past month — during which not a single poll shows Trump over Clinton and most show her up by double digits. Half (49%) of voters polled by Fox News use the word “scared” to describe their reaction to a potential Trump presidency.
• Mr. Trump claims to have “won Hispanics” in the Nevada caucuses, a meaningless achievement in a closed caucus in which Hispanics, who are mostly Democrats, represented a minuscule percentage of participants. In reality, Hispanics despise Trump and will vote against him in record numbers. While Mr. Trump has a slightly more plausible case that he could attract support from blacks, even if true it won’t be enough of a change from decades-long black voting patterns to make a difference. The recent Fox News poll shows an incredible 85 percent of blacks holding an unfavorable opinion of Trump.
• More than a third of Republicans would consider voting third party or not voting at all if Donald Trump is their party’s nominee.
• People view Mr. Trump as turning out the “angry white vote” but he will also turn out many whites to vote against him. Indeed, CNN/ORC measures Trump’s unfavorable rating among whites at about 60 percent, as it is among other groups you may think matter in elections such as: independents, men, women, people with college degrees and people without college degrees, urbanites, suburbanites, rural folks, and people in the Northeast, Midwest, South, and West. Young voters of all races will oppose a man who they perceive as angry, divisive, misogynistic and racist; roughly three quarters of voters under the age of 35 disapprove of Mr. Trump.
• These findings bear repeating as more than one poll duplicates the results: According to Fox News, if the election were held today, Mr. Trump would lose to Hillary Clinton by 11 points, tying among men and winning by only six points among whites (both of those representing a horrendous showing for a Republican) while losing by nearly 20 points among women and losing every age bracket. For comparison, Romney won men by 8 points and white voters by 20 points — and still lost the election due to losing women by 12 points — the 20-point “gender gap” being the largest measured by Gallup in sixty years. (In the same Fox poll, Ted Cruz beats Hillary by three points, winning men by 15 percent and only losing women by seven percent while winning whites by 19 percent.)

These are just some of the reasons that betting odds of a Democrat winning the presidency have risen to over 70 percent as Donald Trump has stabilized his position as the GOP frontrunner. The Democrats are more than a 2-to-1 favorite in November despite how noxious both Democratic candidates are and despite the fact that the Democrats have only won a third consecutive presidential term twice in the history of the modern American parties. (FDR gaining a third term for himself in 1940 and Martin Van Buren’s succeeding two-term Democrat Andrew Jackson in 1836.)

Trump polls even worse against Bernie Sanders than he does against Hillary Clinton, although I believe those numbers to be an artifact of Sanders having had no serious attacks against him during this primary season. If Sanders were the nominee, those numbers would change quickly — although, and I can’t believe I’m saying this, Trump would likely lose even to the ancient socialist.

On a related note, Mr. Trump says that current Trump-Clinton matchup polls are to be discounted because he “hasn’t even started on Hillary yet.” The problem for Donald is that the public already views Hillary as repellant, unethical, and incompetent and yet they still prefer her to him. How much more is to be learned about Hillary Clinton that people don’t already either know or assume about her? (This is why I maintain my view that Bernie Sanders has almost no chance to be the Democratic nominee even if Clinton is indicted.)

On the other hand, as much as people believe they know about Mr. Trump, the opposition research yet to be dumped on his head will be beyond anything he has ever experienced and anything he is prepared for. It’s not as much that he hasn’t started on Hillary as that the Democrats haven’t started on him. (They can start with this man or this woman, just to warm up.)

For those Trump supporters who have over the years chastised Americans who consider electability as a factor in whom to support for president, how can you now support a man who will not only hand Hillary Clinton the White House but likely give Democrats complete control of Congress?

And why do those of you who hate the “establishment” and the way Washington operates today think that Mr. Trump, the quintessential politician-buying establishment figure, is more likely to disrupt the status quo than is Ted Cruz, who has made a career of annoying colleagues by doing just that?

I understand conservatives supporting a truly conservative candidate even if that candidate is an underdog. I understand Republicans supporting someone, warts and all, who can beat a Democrat.

But I don’t understand how, in the face of so much evidence that Donald Trump is neither a conservative nor an electable candidate, otherwise rational and principled right-of-center voters think that they are doing anything other than destroying the country by their support of a narcissistic self-promoting hand-size-fetishizing authoritarian nationalist charlatan who spends half his day on social media and the other half telling us that everyone from the U.S. military to the Mexican government to the news media will bow to his will should he be elected. (For responses to each of these dictatorial impulses, see here, here and here — and a bonus here.)

Despite the understandable frustration and anger of many Americans (and especially many Republicans), our fellow citizens will never elect Donald Trump president. Whether you like Mr. Trump, as my colleague Jeff Lord does, or whether you find him politically repugnant, as I do, if the idea of a President Hillary Clinton frightens you it is imperative that you are honest with yourself about which Republican can actually win in November. That person is not Donald J. Trump.