The longer this campaign lasts, the more I’m ready to believe Donald Trump is the Slim Shady of modern political journalism. He’s been sent here to destroy us. Either that, or he’s glommed onto the fatal weakness at its heart and is doing whatever he can to let it destroy itself.

Trump’s genius has been his willingness to say, do and propose things so outlandish, so unsettling in tone and substance — so disqualifying under the old rules — that they’ve caused the system to malfunction. Trump looks at the mainstream press as a man holding a stack of thick cardboard sheets might look at an office copy machine. He knows if he sticks enough of them through the copier at once, the machine will jam.

This might be the week he gets what he’s been waiting for.

Coverage of Hillary Clinton’s pneumonia and her talk about Trump’s “basket of deplorables” has perfectly illustrated why even some of this nation’s best journalists can sometimes be so very bad at writing about politics.

Dan Balz at the Post is one of the best in the business, but he just couldn’t help hammering Clinton for attacking Trump’s people as “deplorable” on Friday. Attack Trump, he wrote? No problem, he wrote. Attack his people? Major party foul.

What rubbish. Lots of Trump’s supporters are deplorable. There’s nothing wrong with Clinton saying so. Some are racist, some are sexist, some are homophobic, just as she said. Some of his supporters just want to hang Clinton in effigy, or beat up protesters.

But half? I sure hope not. But Clinton conceded right from the top that she was speaking in bald generalities. Besides, she was telling her liberal supporters that while, yes, some Trump voters aren’t reachable because of their biases, millions of his likely voters are not that at all. She said they support him because they are desperate for new leadership, new politics and for prosperity.

She’s right, and the NeverTrumpers who overlook that are making a huge mistake.

Still, by Monday night, NPR’s Mara Liasson was reporting that nothing seemed to be going right for Clinton. And when she took ill on Sunday, and it was revealed that she had known for two whole days that she had walking pneumonia and hadn’t alerted the Republic, it wasn’t just a mistake. It was proof, in many writers’ eyes, that Clinton had trust issues.

But for all his bluster, Trump remains very much a losing candidate. Sure, Clinton’s chances of winning aren’t quite where they were a month ago, when The Upshot put her chances at 89 percent to Trump’s 11. But they have positively soared from where they were in early June and much higher than in late July.

Even over at Fivethirtyeight.com Clinton is doing well. On Tuesday, it reported her chances at 69 percent, to Trump’s 31 percent. Not a lock, but a nail biter? Hardly.

I am less worried about Clinton’s chances than I am about what this election says about the press’s defects. Because for all the talk that the media are biased, I believe the bigger problem for the media is structural. And the biggest flaw is tucked right inside one of the media’s virtues: Modern political journalism can’t abide an unfair fight. It’s set up to value, even demand, a good contest.

Reporters, by instinct and training, look for the middle position. If nature abhors a vacuum, the political press equally abhors an outlier. So if every candidate in modern history has provided tax returns, and Trump doesn’t? Then Trump is in for a beating.

Gary Hart gets caught with a mistress. He’s hounded straight out of the race. Joe Biden lifts some lines from a British pol in a speech; he’s done. George McGovern picks a running mate with a history of depression and shock treatment? So long Thomas Eagleton and hello Sergeant Shriver.

That’s how the media play. You step out of line, and you get hammered. You either step back within the acceptable boundaries, if you can, or you keep getting hammered until you’re done.

But what happens when a candidate never steps back in line? And he doesn’t quit? And no matter how bad you bash him, he keeps giving you more reason?

The press, ever eager for a spot in the middle, stretches the boundaries all the way up to where Trump is. Trump creates a new normal. And so he suddenly finds himself back in the sweet spot. Way back on the other side of the field? That’s Clinton, and every time she takes even the slightest stumble, she’s going to get hammered now, too.

It keeps the race closer, less boring, and it enables the reporters to be right in the middle where they like to be, bashing one side then the other. It feels fair.

Only, it’s not. It’s not fair. And it’s not good journalism, either.

Michael A. Lindenberger is a columnist for the Dallas Morning News.