Donald Trumpadopted Ronald Reagan’s slogan, “Let’s Make America Great Again,’’ but he continues to defy Reagan’s sacred commandment: “Thou shalt not speak ill of another Republican.’’

With good reason. Look what Trump’s latest sacrilege got him: Jeb Bush, watching, Eli Manning-like, as big brother shows him how to win the game. And with that sibling psycho-drama comes the added burden of revisiting the terrorist attack of Sept. 11, 2001, which happened on George W. Bush’s presidential watch, and led to his decision to invade Iraq.

Those issues hobbled Jeb Bush at the start of his campaign, as he tried to prove he was his own man — and not his brother’s keeper. Now, thanks to Trump, they are back in the spotlight.

If Reagan-era conventions applied, Trump has gone so nuclear with the ill-speaking, he should be radioactive. But until voters say so, he’s not. Ever the gambler, he’s betting the passion for political revolution on the right is as real as the one on the left — and that flushing out the establishment represented by the Bush dynasty is the path to victory.

That was clear during last Saturday’s debate, when Trump declared, “Obviously, the war in Iraq was a big, fat mistake. George Bush made a mistake. We can make mistakes. But that one was a beauty. We should have never been in Iraq. We have destabilized the Middle East.’’ Trump continued to attack during a Monday press conference, comparing the argument that Bush kept the country safe after 9/11 to saying that a rival team “scored 19 runs in the first inning, but after that, we played pretty well.’’

Marveling at Trump’s chutzpah now sounds as trite as the sentiment behind Reagan’s famous “It’s morning again in America’’ ad — a theme reprised in a Marco Rubio campaign ad. But Trump’s success, so far, is based on a different kind of self-promotion. Jeb Bush derides it as Trump’s willingness to insult his way to the White House. The problem for all Trump opponents is that some of his insults ring true enough.

Jeb Bush may have a little more zip than he did when Trump first tagged him as “low-energy,’’ but he’s far from electric. As for his brother, it’s hard to deny that on the morning of Sept. 11, George W. Bush did not keep the country safe. Having the former president recount his version of being told when the planes struck the World Trade Center towers is a reminder of the controversy over warnings the Bush administration failed to heed.

And hearing the former president declare “The presidency is a serious job that requires sound judgment and good ideas’’ is not necessarily a boost to the brother who wants to be president. Does Jeb really want to answer yet again for W’s judgment and ideas?

Remember how Jeb Bush struggled to answer questions about the Iraq invasion? First, he said that he, too, would have authorized the invasion. Then he said that, knowing what we know now, mistakes were made. After that, he said we should focus on the lessons learned. And after that, he said the lesson learned was the need for good intelligence.

Pushing Bush back to that turf is win-win for Trump’s quest to make himself great. Making the country great is another matter.

Joan Vennochi can be reached at vennochi@globe.com. Follow her on Twitter @Joan_Vennochi.