Before this presidential campaign began, many people believed that the American public's view of Hillary Clinton couldn't change all that much. Sure, she'd get attacked plenty by her opponents, but after being first lady, a senator, and secretary of state, in the furious glare of the media spotlight since 1991, the voters knew what they felt about her.

That turned out not to be true. While Clinton's approval ratings moved up and down over the course of her quarter-century as a national figure (usually in concert with how close she was to partisan politics), in April 2015, for the first time more Americans told pollsters they had a negative opinion of her than a positive opinion.

It had something to do with the fact that Clinton finally declared her candidacy for the presidency at the beginning of that month. But the real reason was a different story that emerged one month before: her emails.

To put it simply, if Donald Trump becomes president of the United States, Clinton's emails will be the reason. I'm sure that Clinton and those close to her feel that idea is not just unfair, but positively ludicrous. I don't disagree — it is ludicrous. But it's the truth.

When I say it's ludicrous, what I mean is that the 2016 campaign has taken what is essentially a misdemeanor and cast it as though it were one of the crimes of the century. Every presidential candidate and president has some scandals, scandalettes, or at the very least some controversies that they have to navigate. But in the scope of history, this one is minor — laws weren't broken, lives weren't destroyed, there was no behavior shocking to the conscience, and there are at least a dozen things Donald Trump has done that are far, far more serious for what they say about the kind of president he'd be. I'm not going to relitigate the controversy further except to say that while Clinton was certainly wrong to use a private email system for work, it wasn't a crime, and the FBI made the right decision in saying that no reasonable prosecutor would bring charges against her for it.

It did turn out to be one of the most spectacular political mistakes of all time, however.

Look at where Clinton is right now. It isn't just that the polls are close, which they are. But far and away Clinton's biggest problem is that a majority of voters don't believe she's honest and trustworthy. Only about a third say that she is — ratings that put her about as low as Donald Trump on that measure.

By any objective standard, that's positively insane. Clinton says some things that aren't true from time to time, but in this she's little better or worse than most other politicians. Trump, on the other hand, is without a shred of doubt the biggest liar nominated by a major party in living memory. It isn't even close. On an average day, Trump will tell at least a dozen demonstrably provable lies. And unlike other politicians, he'll continue to tell a lie long after it has been pointed out to him, often multiple times, that what he's saying is false. He's positively pathological.

Here's a test: If I asked, you could probably name a half-dozen lies Donald Trump regularly tells or has told lately, right off the top of your head. He just said Hillary Clinton invented the birther controversy, he says thousands of Muslims celebrated 9/11 on rooftops in New Jersey, he says Barack Obama founded ISIS, he says crime is at record levels, he says he opposed the Iraq War before it started, he says the unemployment rate is actually 42 percent... I could go on.

Now: Off the top of your head, name three specific lies Hillary Clinton has told. You can't, can you?

Again, I'm not saying she's never said anything untrue. But we're talking about two candidates who are worlds apart on this score. And yet the public sees them as basically equally dishonest.

How did this happen? Here's Harvard professor Thomas Patterson discussing some research he recently conducted on coverage of the campaign:

My analysis of media coverage in the four weeks surrounding both parties' national conventions found that her use of a private email server while secretary of state and other alleged scandal references accounted for 11 percent of Clinton's news coverage in the top five television networks and six major newspapers, including the Los Angeles Times. Excluding neutral reports, 91 percent of the email-related news reports were negative in tone. Then, there were the references to her character and personal life, which accounted for 4 percent of the coverage; that was 92 percent negative.

Or let's take another data point. In a recently released NBC News poll, 69 percent of voters said they had concerns about Donald Trump's comments about women, immigrants, and Muslims; 66 percent said they had concerns about Trump having the temperament to be commander-in-chief; and 64 percent said they had concerns about Clinton's email. So Clinton's emails are about as serious as Trump being a huge bigot and possibly starting World War III over a mean tweet someone sent him.

It wasn't a conspiracy that produced this state of affairs, but it might as well have been. On one hand you had Republicans, who found in the email issue a controversy that could do for them what Benghazi wasn't able to (and not for lack of trying, heaven knows): provide something they could hammer away at, whether there was any serious malfeasance or not, and have it become a shorthand for the idea that Clinton is irredeemably corrupt. Trump himself, with his usual commitment to precision and truth, claims that she's obviously guilty of numerous (unnamed) crimes, and his crowds chant "Lock her up! Lock her up!" (2016's version of "Burn the witch!") whenever her name comes up.

Meanwhile, the press not only devoted copious column inches and cable news hours to the email story, it tended to present it as nefarious whether the latest development showed evidence of any wrongdoing or not. After months and months of this, the public is left with a vague but persistent sense that Clinton did something terrible, even if they couldn't tell you what it was. When Gallup asks voters to name the most recent thing they can recall hearing about Clinton, the most common response is almost always "emails."

Hillary Clinton should be accountable for her decision to use a private email system. That mistake started this whole thing. And she's still more likely than not to win this election. But if she loses, it will mean that this absurdly overblown controversy made Donald Trump president of the United States, with who knows what kind of destruction to follow.