Stop attacking Donald Trump's politics. Attack his character instead.

Some Republicans, at least, are starting to cotton up to the idea that if you don't want someone to win, maybe you attack him. Marco Rubio has begun attacking Donald Trump on the stump. It's a pretty timid jab, but a significant one for the very message-disciplined candidate who has tried to run a positive campaign.

The problem is that he's been doing it wrong. Conservatives have insisted on attacking Trump on policy, and in one direction: charging him for not being right-wing enough.

In what may be the most frustrating news to come out of a very infuriating election cycle, Politico describes the reasons why the GOP's mega-donors and heavy hitters are afraid of launching a wave of attack ads. Only 4 percent of the $238 million in advertising spent by big-money groups so far has targeted Trump. One reason is sheer cowardice (they're afraid Trump might hit back). But another reason is that previous ads didn't work.

But these ads are practically designed not to work, because they only reinforce Trump's message. The ads either decry Trump for being politically incorrect, or describe him as not a traditional conservative. Both things are precisely his appeal, and both boil down to "He's not one of the guys you hate." The ads are saying: "All those reasons you like Trump? They're really true!"

The reason why Trump shouldn't be president, fundamentally, is not his position (or lack thereof) on this or that issue. Trump doesn't care about the border wall or ObamaCare (whatever his position on it is this week). The reason Trump shouldn't be president is because he's probably a sociopath.

So this is what the attack ads should focus on. The ads should focus on what people like about him, and invert it. As Ross Douthat put it in a column last month:

So don't tell people that he doesn't know the difference between Kurds and the Quds Force. (They don't either!) Tell people that he isn't the incredible self-made genius that he plays on TV. Tell them about all the money he inherited from his daddy. Tell them about the bailouts that saved him from ruin. Tell them about all his cratered companies. Then find people who suffered from those fiascos — workers laid off following his bankruptcies, homeowners who bought through Trump Mortgage, people who ponied up for sham degrees from Trump University. (...) If you want to persuade his voters that his "New York values" are a problem for them, put his alleged dealings with the Mafia on the table. [The New York Times]

Would these ads work? Well, they just might work enough to puncture his aura of inevitability and maybe, just maybe, keep his ceiling low enough to allow a non-Trump candidate to break through. They sure as heck would work better than doing nothing.

If not now, we'll find out how well they work once Trump has the nomination locked up and Hillary Clinton starts airing them.