Hillary Clinton has drawn the most bizarre, unstable and unsuitable Republican opponent in American history. Yet she is barely ahead of Donald Trump in the polls.

I sit in conversations with the most fervent of Hillary supporters, and most of them are exasperated at her inability to wrap this thing up. As you get to the inner circle of Hillary intimates, the tendency is to blame the media. But there is also the sense that she brings her troubles upon herself.

What the hell is at work here?

First, there is an element of sheer bad luck. The rightwing keeps up a drumbeat questioning Hillary’s stamina, health and strength to do the job — and right on cue she comes down with pneumonia.

NBC’s Matt Lauer turns out to be a total dope, and his dopiness takes the form of obsessing on Clinton’s emails and letting Trump get away with saying that he admires Vladimir Putin more than he admires the President of the United States.

Over to you, Matt. Uh, Matt?

Second, there is the odd gap between the public Hillary and the private one. Everyone who has worked with Clinton says she is terrific — warm, funny, brilliant, caring, conscientious, well-informed, loyal to a fault.

I’ve been in small events with her only on a couple of occasions, but both times that description rang true. Yet the public Clinton often comes across as a composite creation — scripted, not quite authentic, a little tense.

That shouldn’t matter, but it does. Barack Obama, in one of the genuinely wounding lines of the 2008 campaign, got at that vulnerability in the last debate of the New Hampshire primary when the moderator was asking about Hillary’s warmth and Obama ad libbed, “You’re likable enough, Hillary.”

In the short run, that cruel touch of faint praise prompted a backlash that may have cost Obama the New Hampshire primary. But it accurately captured a weakness that continues to haunt Clinton: In politics, it turns out that “likable enough” is not, in fact, likable enough. Not by a long shot.

The New York Times recently sent a reporter to Ohio’s most affluent county to ask swing voters about Trump versus Clinton. Several of them could not abide Trump, but were not ready to vote for Clinton. They just didn’t like her.

The fate of the world should not hinge on a presidential election as a popularity contest, but that’s how politics often works.

What can Clinton do about it, at this late date? She is 68, her personality and operating style were formed long ago. Not a lot.

It’s also the case that the problems that keep coming back to haunt her were baked into the cake long ago. We can’t undo those emails, or the FBI’s outrageous decision not to recommend a prosecution but to publically excoriate her nonetheless.

We can’t roll back the tape and recommend that she exit from the Clinton Foundation long ago, and not take those bloated honoraria from Goldman Sachs.

Why do the Clintons continue to take these chances? If the public decides, rightly or wrongly, that you cut corners, it’s hard to live that down. Bill’s nickname, Slick Willie, didn’t stick because he shot a great game of pool.

My most fervent Clinton loyalist friends say that the Clintons are held to a higher standard than other public figures; that nobody can prove quid pro quos in exchange for donations to their foundation or the honoraria; that no harm to national security came from the email thing.

Fair enough, but appearances matter. Why hand your enemies a loaded gun? This is how voters make up their minds about your character.

Barack Obama, by contrast, has been a model of probity. Not a whiff of scandal in his public or private life. He gets hardly any credit for that, but I suspect it’s part of why his approval ratings are in positive territory and hers are not.

Let’s stipulate: Trump’s misdeeds are of a whole other order than those of Clinton. The man professes concern for working people but declares bankruptcy multiple times and stiffs his contractors as part of his business model. He cheats students who gullibly go into debt to enroll in the fraudulent Trump University.

He makes statements — “I have a secret plan to deal with ISIS” — that would bring down ordinary politicians in a hail of ridicule. Uniquely, he won’t release his taxes.

Yet the press treats his stuff and hers as if both were approximately equal. The bar has been so lowered that when Trump can get through a day without saying something idiotic, it is treated as an achievement.

Hillary Clinton would make a fine president. She has the experience, the compassion for the downtrodden, the expertise. For some of us, she represents too much continuity when the country is desperate for change. But compared to Donald Trump — are you kidding?

First, however, she has to get elected.

A couple of weeks ago, it was looking as if we could relax. Trump couldn’t stay on script, the race was locking in favor of Clinton. Now it’s a nail-biter again.

I have the sense that on Election Day, Clinton will still pull it out. But I sure wish she were a more effective candidate. The fate of the world should not depend on Donald Trump’s penchant for blurting out nonsense.

Robert Kuttner is co-editor of The American Prospect and professor at Brandeis University’s Heller School. In his spare time, he writes musicals. His latest book is Debtors’ Prison: The Politics of Austerity Versus Possibility.

Like Robert Kuttner on Facebook.