There are many, many reasons to abhor Donald Trump's presidential campaign, but there's at least one reason to appreciate it, for now: his constant and merciless trolling of Jeb Bush that is currently tanking Bush's shot at the presidency. In some sense, Trump is doing democracy a service by helping ensure we will not have to suffer the embarrassment of having a third Bush family member as president within two decades.

Trump will attack Jeb for his support for the Iraq War, but if Bush lightly criticizes George W Bush, Trump questions why he would throw his brother under the bus. Trump attacks Jeb for his record in Florida, rips him for his $1.3m "no show job" at Lehman Brothers after he left the governorship. He calls Jeb out for being "100% CONTROLLED" by his wealthy donors, and when a few donors recently left Jeb's campaign, Trump made fun of him for that too.

But it's repetition of his now infamous and nebulous phrase -- that Bush is a "low-energy guy" who could not handle the rigors of the presidency -- that has become a daily occurrence and clearly gotten under Bush's skin. Trump is constantly finding new ways to say it or sneaking it into statements, even those that aren't targeted at Bush himself.

He has been running half-bizarre half-amazing, extremely low-budget Instagram campaign commercials, the latest of which shows a Jeb supporter falling asleep at one of his rallies. It's an instant classic in the genre. Trump's previous less-than-15-second Instagram ads targeting Jeb declared "Enough is Enough -- no more Bushes!" and featuring Barbara Bush saying we don't need another Bush presidency are just as cutting (she later recanted when it was clear Jeb would run).

During a recent 35-minute interview with the Washington Post, Trump criticized Jeb and the two other Bush presidents a total of 33 times (which the Post helpfully documented in a separate article). As one anonymous Trump associate told the Post, Trump is "driven and he has two goals: one, to be elected president, and two, to have Jeb not be president." The former remains a terrifying prospect, but the latter is something a lot people can get behind.

While Trump remains strongly disliked by the vast majority of Americans who are not members of the Republican party, Jeb is often pitched as the "moderate" candidate who can appeal to a large swath of voters. Yet in substance, he is far more dangerous than Trump.

Jeb said last week the person he looked to most for Middle East advice is the same man who led the country into two disastrous wars that we are still paying for more than a decade later, George W Bush. On the Late Show with Stephen Colbert on Tuesday, Jeb said he was like his brother, except "more conservative." So if you ever thought George W Bush's wars in the Middle East were spot on, but wished he cut taxes for the richest people a little more, Jeb Bush is the candidate for you.

Thankfully, Trump has exposed Bush, not only on substance but as someone who is just not a good politician. Jeb's campaign knows it. His donors know it. And the voters certainly have been paying attention: Bush's poll numbers have dropped so low, it's hard to believe even the most conventional wisdom-spewing political pundits can still call him the "front runner" with a straight face. He's dropped to fifth or sixth and to single digits in almost all the recent polls in the early primary states. He seems flustered on the trail, and no one can point to a path by which he recovers from this, despite remaining the DC elite's odds-on favorite.

As embarrassing and terrifying as a Trump presidency would be, the virtual anointing of a Bush family monarchy could be far worse, and so at least for now, I hope Trump keeps swinging away.