Okay, now THIS is the sort of Republican trickery we've been waiting for: The GOP is great at launching terrible attacks against Democrats, and now they're finally figuring out the science and art necessary for taking down Donald Trump.

At last, the evil henchmen are revving up the machines that they used to take down Kerry and smear Obama, and pointing them at the man who must be stopped by any means necessary. It's a mix of advertising and statistics, both of which we're likely to see evidence of over the next few weeks.

The statistical strategy seems to rely on Trump falling short of the required delegates so they can have a contested convention, and that strategy is being masterminded by the "Our Principles PAC," which is basically Mitt Romney.

Our Principles has already dumped a couple million dollars into Trump attacks, and now they've released a super-complicated memo about how to stop him at the convention.

Basically it boils down to this: as long as they can derail the campaign in next week's primaries, he should fall just short of the automatic-nomination threshold. And then they can take him down ... somehow.

Trump's statistical vulnerability, they point out, is that he's claimed less than half of the available delegates so far, in part because the race is so fractured. Ohio will be crucial, since it's winner-take-all and Kasich is close on Trump's heels. For the love of God, Kasich, don't fuck this one up.

The math on these delegate counts is like an elaborate Mensa puzzle, because that's the stupid election system we're stuck with. For Trump to pull off the nomination right now, he'd have to win 54% of the remaining delegates. So far he's picked up 23%, which doesn't sound like much but everyone else is doing even worse.

And even if he picks up both Florida and Ohio, he could still win a bunch of other states and still fall short.

Okay, great. Then what? We get to the convention, there's a big fight, and ... ? What happens next, Mitt? Trump will still have the most delegates, so how are you going to stop him?

With dirty tricks, hopefully. And this is where the Republican masterminds will have to do their most skillful work yet, with hit pieces such as this one:

They'd also have to engage in a "rules revolt," twisting a bunch of convention rules at the last minute. (For example, some technical details about who's eligible to be nominated against the frontrunner, a rule that was established in 2012 to spare Romney the embarrassment of having to deal with Rand Paul.)

There are certainly a lot of sneaky, underhanded, not-quite-illegal tricks that could put a few bumps in the road for Trump at the convention. And if anyone's capable of that kind of malfeasance, it's you, Republicans.